RIPARIAN VEGETATION OF THE MONTANA YELLOWSTONE
AND CATTLE GRAZING IMPACTS THEREON
By
Margaret Joy Slack Eggers
A thesis submitted in partial fulfillment
of the requirements for the degree
of
Master of Science
in
Biological Sciences
MONTANA STATE UNIVERSITY
Bozeman, Montana
August 2005
© COPYRIGHT
by
Margaret Joy Slack Eggers
2005
All Rights Reserved
ii
APPROVAL
of a thesis submitted by
Margaret Joy Slack Eggers
This thesis has been read by each member of the thesis committee and
has been found to be satisfactory regarding content, English usage, format,
citations, bibliographic style, and consistency, and is ready for submission to the
College of Graduate Studies.
Dr. Theodore Weaver
Approved for the Department of Ecology
Dr. David Roberts
Approved for the College of Graduate Studies
Dr. Joseph J. Fedock
iii
STATEMENT OF PERMISSION TO USE
In presenting this thesis in partial fulfillment of the requirements for a
master's degree at Montana State University, I agree that the Library shall make
it available to borrowers under rules of the Library.
If I have indicated my intention to copyright this thesis by including a
copyright notice page, copying is allowable only for scholarly purposes,
consistent with "fair use" as prescribed in the U. S. Copyright Law. Requests for
permission for extended quotation from or reproduction of this thesis in whole or
in parts may be granted only by the copyright holder.
Margaret Joy Slack Eggers
August 12, 2005
iv
ACKNOWLEDGEMENTS
I am grateful to my major professor, Dr. Tad Weaver, for his long standing
support of this research Dr. Weaver, Dr. Scott Creel, Dr. Clayton Marlow and
Carol Johnson all contributed constructive criticism of this manuscript. I thank
Dr. John Rumely, for teaching me to identify grasses and sedges, for
identification of difficult specimens and verification of many of the plants
collected. His love of plants is inspiring and contagious, and will always stay with
me. I also appreciate Dr. Jack Plaggemeyer for his help with the statistics and
Ken Aho for his help with the ordinations. I am grateful to Sara Young,
Dr. Elisabeth Swanson, Dr.Catherine Zabinski and Dr. Penelope Kukuk for their
moral support and mentorship, which has helped sustain me. Dr. Matt Lavin and
Catherine Siebert, of MSU’s herbarium, generously contributed their time and
expertise. Additionally, I thank Dionne Pretty On Top, the most outstanding field
and lab assistant I have ever had.
I am particularly grateful to the many ranchers who shared their
knowledge of the land and the Yellowstone, and kindly allowed us access to their
pastures. The Montana Fish, Wildlife and Parks also allowed us research access
to their fishing access sites.
Support was provided by the Environmental Protection Agency through a
STAR graduate fellowship, award#U915792, Dr. Theodore Weaver, P.I.
Research support was provided by NSF’s UMEB grant #PG-5637-O2, Dr.
Penelope F. Kukuk, P.I. Faculty development support was provided by the
National Institute for Health’s Initiative for Minority Student Development grant #
R25 GM56806, through MSU Bozeman’s American Indian Research
Opportunities program; by a fellowship from NSF’s Center for Learning and
Teaching in the West at MSU Bozeman; and by Little Big Horn College (LBHC),
thanks to Dr. David Yarlott’s and Dr. Donna Wald’s support.
Finally, I especially thank my family for always standing by me.
v
This thesis was developed under a STAR Research Assistance
Agreement No. U915792 awarded by the U.S. Environmental Protection Agency.
It has not been formally reviewed by the EPA. The views expressed in this
document are solely those of Margaret Eggers and the EPA does not endorse
any products or commercial services mentioned in this publication.
vi
TABLE OF CONTENTS
1. INTRODUCTION............................................................................................ 1
Hypotheses ..................................................................................................... 2
2. LITERATURE REVIEW ................................................................................... 5
Values ............................................................................................................. 5
Riparian Vegetation of the Northern Plains ..................................................... 5
Disappearing Resource................................................................................... 7
Grazing Effects................................................................................................ 8
Grazing Effects on Woody Species ........................................................... 9
Mechanisms of Shrub Damage .......................................................... 12
Grazing Effects on Herb Cover/Production .............................................. 13
Grazing Effects on Composition: Natives vs. Exotics .............................. 14
Grazing Effects on Species Diversity ....................................................... 16
Effects on Litter and Bare Ground ........................................................... 18
3. DESCRIPTION OF STUDY AREA ................................................................ 19
4. METHODS..................................................................................................... 24
Overall Sampling Design............................................................................... 24
Sampling ....................................................................................................... 25
Community Composition ............................................................................... 27
Environmental Sampling ............................................................................... 29
Climatological Data .................................................................................. 29
Height Above Water................................................................................. 30
Depth to Gravel........................................................................................ 30
Soil Sampling........................................................................................... 31
Gravel Measurements.............................................................................. 32
Statistics........................................................................................................ 33
5. RESULTS ...................................................................................................... 35
Vegetation and Environment of Ungrazed Communities: Gravel Bars.......... 35
Distribution............................................................................................... 35
Community Composition.......................................................................... 35
Vegetation Cover ..................................................................................... 36
Environment............................................................................................. 38
Vegetation and Environment of Ungrazed Communities: Sandbars ............. 39
Distribution............................................................................................... 39
Community Composition.......................................................................... 39
vii
TABLE OF CONTENTS - CONTINUED
Vegetation Cover ..................................................................................... 41
Environment............................................................................................. 43
Vegetation and Environment of Ungrazed Communities: Salix exigua ........ 43
Distribution............................................................................................... 43
Community Composition.......................................................................... 44
Vegetation Cover ..................................................................................... 46
Environment............................................................................................. 48
Vegetation and Environment of Ungrazed Communities:
Populus angustifolia (Narrowleaf Cottonwood) ............................................. 49
Distribution............................................................................................... 49
Community Composition.......................................................................... 50
Vegetation Cover ..................................................................................... 52
Environment............................................................................................. 54
Vegetation and Environment of Ungrazed Communities:
Populus deltoides (Plains Cottonwood)........................................................ 55
Distribution............................................................................................... 55
Community Composition.......................................................................... 55
Vegetation Cover ..................................................................................... 57
Environment............................................................................................. 58
6. DISCUSSION ................................................................................................ 60
Ungrazed Vegetation .................................................................................... 60
Composition............................................................................................. 60
Summary Description............................................................................... 60
Species Richness and Constancy Compared Across Vegetation Types ...... 62
Diversity (Species Richness) in the Yellowstone River Riparian.............. 62
Lateral Variation in Species Richness ................................................ 65
Longitudinal Variation in Species Richness........................................ 68
Species Constancy Along the Yellowstone ................................................... 69
Native/Exotic Comparison Across Vegetation Types .................................... 71
Evolution of Lower Yellowstone Riparian Communities, 1980-2000 ............. 76
Gravelbars ............................................................................................... 78
Sandbars ................................................................................................. 78
Both River Edge Communities................................................................. 79
Salix exigua Thickets ............................................................................... 80
Mature Populus deltoides Community ..................................................... 82
Grazing Effects.............................................................................................. 84
Gravelbar Communities ........................................................................... 85
Dominance ......................................................................................... 85
Richness............................................................................................. 87
Exotic Presence ................................................................................. 87
viii
TABLE OF CONTENTS - CONTINUED
Environment ....................................................................................... 88
Sandbar Communities ............................................................................. 88
Dominance ......................................................................................... 88
Richness............................................................................................. 89
Exotics................................................................................................ 89
Environment ....................................................................................... 89
Salix exigua (Sandbar Willow) Thickets/Communities ............................. 90
Dominance ......................................................................................... 90
Richness & Exotics............................................................................. 93
Environment ....................................................................................... 93
Populus angustifolia Communities........................................................... 93
Dominance ......................................................................................... 94
Richness............................................................................................. 96
Exotics................................................................................................ 97
Vegetation Overview .......................................................................... 97
Environment ....................................................................................... 97
Populus deltoides Communities............................................................... 99
Dominance ......................................................................................... 99
Richness........................................................................................... 102
Exotics.............................................................................................. 102
Environment ..................................................................................... 103
Summary of Grazing Effects .................................................................. 103
Comparison of Environmental Factors ........................................................ 106
Height Above Water............................................................................... 107
Depth to Gravel...................................................................................... 108
Calcium Carbonate and pH.................................................................... 110
Soil Development Measures: Organic Carbon and Nitrogen ................. 111
Soil Texture............................................................................................ 113
Electrical Conductivity............................................................................ 114
Vegetation/Environment Relations .............................................................. 114
Plains Cottonwood Reproduction on the Yellowstone................................. 116
Climate Change? ................................................................................... 117
Hydrologic Change ................................................................................ 118
Sediment Pollution ................................................................................. 119
Recreation ............................................................................................. 120
7. CONCLUSIONS .......................................................................................... 122
Ungrazed Riparian Vegetation .................................................................... 122
Grazed Riparian Vegetation ........................................................................ 124
LITERATURE CITED ....................................................................................... 126
ix
TABLE OF CONTENTS - CONTINUED
APPENDICES .................................................................................................. 141
APPENDIX A: TABLES .............................................................................. 142
APPENDIX B: FIGURES............................................................................ 236
x
LIST OF TABLES
Table
Page
1.
Basin Characteristics and Annual Streamflow Statistics at
Selected Sites, Yellowstone River Basin ............................................. 143
2.
Montana Precipitation and Temperature Data...................................... 144
3. List of Research Sites and their Locations,
Elevations and River Mile ...................................................................... 145
4.
Vascular Plant Species of Yellowstone River
Riparian Communities.......................................................................... 150
5.
Vegetation of Ungrazed Gravelbar Sites:
Releve and Frequency Data ................................................................ 159
6.
Vegetation of Ungrazed Gravelbar Sites:
Releve and Cover Data........................................................................ 163
7.
Gravel Measurements for Ungrazed Gravelbar Sites........................... 167
8.
Environmental Variables at Ungrazed Sites ......................................... 168
9.
Vegetation of Ungrazed Sandbar Sites:
Releve and Frequency Data ................................................................ 169
10. Vegetation of Ungrazed Sandbar Sites:
Releve and Cover Data........................................................................ 174
11. Vegetation of Ungrazed Salix exigua Sites:
Releve and Frequency Data ................................................................ 177
12. Vegetation of Ungrazed Salix exigua Sites:
Releve and Cover Data........................................................................ 182
13. Vegetation of Ungrazed Populus angustifolia (Narrowleaf
Cottonwood) Sites:Releve and Frequency Data .................................. 187
14. Vegetation of Ungrazed Populus angustifolia (Narrowleaf
Cottonwood) Sites: Releve and Cover Data ........................................ 191
xi
LIST OF TABLES - CONTINUED
Table
Page
15. Vegetation of Ungrazed Populus deltoides (Plains Cottonwood)
Sites: Releve and Frequency Data ...................................................... 194
16. Vegetation of Ungrazed Populus deltoides (Plains Cottonwood)
Sites: Releve and Cover Data.............................................................. 198
17. Comparison of Cover, Richness and Percent Non-native Species
Across Ungrazed Riparian Plant Communities .................................... 202
18. Species Occurring with 20% or Less Constancy
Across Ungrazed Riparian Plant Communities .................................... 204
19. Non-native Species Found in Riparian Plant Communities,
Both Ungrazed and Grazed Sites. Grouped by Families .................... 205
20. Number of Plant Communities in which each Species Occurs,
Segregated by Native/Non-native. Ungrazed Sites Only .................... 208
21. Comparison of Ungrazed and Grazed Gravelbar Sites,
Cover Data and T Test Results............................................................ 214
22. Comparison of Ungrazed and Grazed Sandbar Sites,
Cover Data and T Test Results............................................................ 217
23. Comparison of Ungrazed and Grazed Salix exigua Sites,
Cover Data and T Test Results............................................................ 220
24. Comparison of Ungrazed and Grazed Populus angustifolia Sites,
Cover Data and T Test Results............................................................ 224
25. Comparison of Ungrazed and Grazed Populus deltoides Sites,
Cover Data and T Test Results............................................................ 227
26. Comparison of Cover, Richness and Percent Non-Native Species
Across Grazed Riparian Plant Communities........................................ 231
xii
LIST OF TABLES - CONTINUED
Table
Page
27. Environmental Variables at Ungrazed vs. Grazed Sites,
By Riparian Plant Community .............................................................. 233
28. Shrub Cover of Ungrazed vs. Grazed Populus deltoides Sites,
Releve and Cover Data. Sites are Segregated by Ungrazed/
Grazed, Then in Order by DBH............................................................ 234
29. Species Richness Found by Sampling Lower Yellowstone River
Sites by Two Methods .......................................................................... 236
xiii
LIST OF FIGURES
Figure
Page
1. The Yellowstone River Basin ................................................................. 238
2. Potential Natural Vegetation of the Yellowstone River Basin ................ 239
3. Physiographic Provinces of the Yellowstone River Basin ..................... 240
4. Average Annual Precipitation, Yellowstone River Basin ....................... 241
5. Mean Daily Precipitation and Temperature At Selected Stations
Along the Yellowstone River .................................................................. 242
6. Generalized Geology of the Yellowstone River Basin ........................... 243
7. Sites Along the Yellowstone River ........................................................ 244
8. Gravelbar at Emigrant West Fishing Access Site. Seedlings of
Populus angustifolia are the Dominant Cover........................................ 246
9. Gravelbar at Emigrant West Fishing Access Site,
Showing Both Sand and Cobble Substrates ......................................... 246
10. Gravel Size Distribution on Gravelbars ................................................ 247
11. Sandbar at Seven Sisters Wildlife Management Area.......................... 248
12. Salix exigua Thicket with Taller Salix amygdaloides Behind It.
Far West Fishing Access Site .............................................................. 248
13. Populus angustifolia Forest at Grey Owl Fishing Access Site .............. 249
14. Populus deltoides Forest at Far West Fishing Access Site .................. 250
15. Grass Growing in a Sandy Patch of a Gravelbar, at Emigrant
West Fishing Access Site..................................................................... 251
16. Succession on a Gravelbar near Emigrant, Montana ........................... 252
17. Growth of Populus angustifolia Community from Gravelbars ............... 253
18. Growth of Populus deltoides Community from Sandbars ..................... 254
xiv
LIST OF FIGURES - CONTINUED
Figure
Page
19. Height Above Water of Research Sites ................................................ 255
20. Depth to Gravel at Research Sites ....................................................... 256
21. Soil CaCO3 Percent Equivalency at Research Sites ............................ 257
22. Soil pH at Research Sites .................................................................... 258
23. Soil Percent Organic Carbon at Ungrazed Sites .................................. 259
24. Soil Percent Nitrogen at Ungrazed Sites .............................................. 260
25. Soil Texture: Percent Sand at Ungrazed Sites ..................................... 261
26. Soil Texture: Percent Silt at Ungrazed Sites ........................................ 262
27. Soil Texture: Percent Clay at Ungrazed Sites ...................................... 263
28. Soil Electrical Conductivity at Research Sites ...................................... 264
29. Severely Grazed Sandbar Willows, Foothills Zone .............................. 265
30. Ordination of Ungrazed vs. Grazed Gravelbars ................................... 266
31. Ordination of Ungrazed vs. Grazed Sandbar Sites .............................. 267
32. Ordination of Ungrazed vs. Grazed Salix exigua Sites......................... 268
33. Ordination of Ungrazed vs. Grazed Populus angustifolia Sites ............ 269
34. Ordination of Ungrazed vs. Grazed Populus deltoides Sites................ 270
35. Ordination of Populus angustifolia, P. deltoides and
P. acuminata Communities .................................................................. 271
xv
ABSTRACT
The objects of my research were two. To describe ungrazed vegetion of
thirty sites well dispersed along the 500 mile length of the Yellowstone River.
And to measure the effects of gazing on this vegetation by describing/comparing
vegetation of these ungrazed ‘control’ sites with the vegetation of nearby grazed
sites.
Vegetation of the Yellowstone consists of three lateral bands on open
shore (gravel or sandbar), willow thicket, and cottonwood forest. Their
appearance on successively older deposits suggests control both by decreasing
water availability (greater depth to water on inland sites with ‘over deposits’) and
increasing age (overtopping, first by willow and then by cottonwood, and
accumulation of shrubs). The primary longitudinal (downstream) change
between foothill and plains sites, probably driven by decreasing rainfall, was the
change of forest dominant from P. angustifolia to P. deltoides. The apparent
failure of P. deltoides reproduction could eventually eliminate the forest zone.
Grazing affects all of the five communities identified. With grazing, overall
cover decreased in every vegetation type, with the greatest losses in sandbars,
willow thickets and P angustifolia forests. Cottonwood seedlings were grazed on
bars and in willow thickets. Cover of hydric (Salix spp., Cornus, Ribes spp.) and
mesic (Symphoricarpos) native shrubs was significantly reduced. Rosa spp. lost
cover with trampling. Invasive shrubs Russian olive and tamarisk, downstream,
are apparently unaffected by grazing, except indirectly as grazing reduces their
competition. Forb cover was most affected in Populus forests, with natives
declining and non-natives increasing with grazing. Non-native grasses, the
dominant herbs in cottonwoods, become more dominant with grazing.
Observation of the exotics present emphasized the equal or greater
impact of their invasion. Cover of exotics rises laterally from shore (50% with
equal grass/forb composition) through willow thicket (70%, mostly exotic grass)
to cottonwood forest (76-78%). The diversity of exotic herbs increases (laterally
and downstream.). In the shrub layer Russian olive and tamarisk, pests in the
American Southwest, increased greatly in the Plains in the 1980-2000 period and
have a potential to dominate the forest and willow zones respectively. The
ecosystem impacts of exotic increase will likely modify aesthetics, wildlife,
and ranching drastically.
1
INTRODUCTION
The primary object of our project is to identify and evaluate the effects of
grazing management on riparian vegetation within riverine corridors of the
northern foothills and plains. The work is stimulated by the knowledge that
riparian vegetation of high plains rivers serves our aesthetic, recreational,
economic and water quality needs and provides critical fish and wildlife habitat
(Mosley et. al. 1997).
Our review of relevant literature (see below) examines our knowledge of
the effects of grazing - - the major industry of the region- - on riparian community
composition and structure.
The impacts on trees, shrubs, forbs and graminoids
are discussed, as well as the impacts of grazing on species diversity and native
vs. non-native dominance in the communities.
To examine the effects of grazing, we need to find contrasting treatments
and, in doing so, to control for other variables, especially geographic variation in
water and temperature conditions. There are three primary dimensions in
riparian ecosystems: lateral – perpendicular to the river, longitudinal - along the
length of the river, and vertical (above to below ground) (Vannote et. al. 1980).
The lateral gradient (sandbar and/or gravelbar, willow, and cottonwood) extends
from plentiful to scarce water and from recent to long ago community
establishment (Boggs and Weaver 1992). Vegetation simultaneously varies
down river as the climate warms and dries from conifer through foothill to plains
2
ecosystems (Zelt 1999). Simultaneously vegetation in any environmental type
varies among grazing treatments due, at least, to amount of forage removal,
season of removal and selection in that removal.
Our specific objectives are thus to 1) identify and describe riparian
vegetation/ecosystem types of ungrazed or little grazed riparian plant
communities of northern foothills and plains to provide a well-controlled basis for
comparing grazing treatments in each type; 2) describe the physical
environments of these communities to verify environmental homogeneity of the
types and identify environmental differences among them; 3) compare ungrazed
and grazed examples of each type to determine/document effects of grazing; and
4) conduct our study over a large scale (500 miles of river) to encompass the
inherent variability of riparian sites.
Hypotheses
Our description of ungrazed riparian vegetation revolves around five
hypotheses. We use three base hypotheses in our test for grazing effects. And
we examine several factors as potential controls of vegetation distribution.
Our baseline description of ungrazed riparian vegetation is centered on
five hypotheses. 1. Overall species richness/site will fall laterally from bar
through willow to cottonwood vegetation. 2. Non-native richness will fall with
increasing lateral distance from the river as introductions decline and disturbance
3
increases. It will rise longitudinally downriver due to a larger seed bank and
ameliorating conditions. 3. The percent low constancy species will fall with
increasing lateral distance form the river due to reduced introductions and
disturbance. 4. Native and non-natives will be equally likely to be low constancy
species. 5. Community composition is constant though time, i.e. similar between
Boggs 1980 and Eggers 2001.
Our hypotheses with respect to grazing effects on riparian vegetation are
three: 1. Species richness/site will not differ between ungrazed and grazed in
any vegetation type.
2. Vegetation cover will generally decrease with grazing:
a) Total vegetation cover will decrease with grazing in every vegetation type;
b) Tree seedling cover will decrease with grazing, in bar and willow communities;
c) Shrub cover will decrease with grazing, in every vegetation type; d) Forb
cover will not vary between grazed and ungrazed sites, in any vegetation type;
and e) Graminoid cover will decrease with grazing, in every vegetation type.
3. Grazing will reduce the cover of natives and increase the cover of non-natives.
a) Native shrubs, forbs and graminoid cover will decrease with in every
vegetation type; and b) Non-native forb and graminoid cover will increase with
grazing, in every vegetation type.
Our hypotheses regarding environmental control of vegetation distribution
are three: 1. Water availability- - as indexed by height above water and depth to
gravel - - will decrease laterally from bar to willow to cottonwood.
2. Organic
matter - - as indexed by soil organic carbon and nitrogen - - will increase with
4
stand age from bar to willow to cottonwood, due to stand aging. 3. Other
factors, i. e. CaCO3, pH, and soil texture, will not show lateral or longitudinal
patterns.
5
LITERATURE REVIEW
Values
Riparian areas contain some of our country’s most valuable ecosystems.
Though small in area, they have high productivity and biodiversity - due in part to
their high physical variability, surface and subsurface water, and rich soils (Green
and Kauffman 1995; Fleischner 1994; Ohmart 1996). Riparian zones and their
streams comprise less than 1% of the 11 arid Western states (US-GAO 1988),
yet they are a critical source of water for riparian plants, wildlife, livestock and
humans (Armour et. al. 1994). Riparian ecosystems provide critical functions of
recharging groundwater, maintaining streamflow and stream temperatures,
protecting water quality by filtering sediments and excess nutrients, stabilizing
streambanks, attenuating floods, and providing habitat for wildlife and fish
(Kauffman and Krueger 1984).
Riparian Vegetation of the Northern Plains
The diversity of riparian plant communities is maintained by the erosion
and deposition of sediments by rivers. The faster the rate of meandering, the
higher the proportion of pioneer and early seral stages in relation to later seral
and climax communities (Hansen et. al. 1988). In Montana, deposits of fresh
6
alluvial materials are colonized by Populus spp. and Salix exigua (sandbar
willow). These species have delicate seeds, and require a constantly moist
surface for seedling establishment (Wilson 1970). As these seedlings grow, a
dense thicket of Salix exigua develops. Populus deltoides seedlings in these
thickets overtop the willow, and eventually form young cottonwood stands. In
eastern Montana, as the trees mature, an understory of smaller trees and shrubs
develops. This can include Fraxinus pennsylvanica, Juniperus scopulorum,
Symphoricarpos occidentalis, Rosa woodsii and other species (Boggs 1984;
Boggs and Weaver 1994). Although the research on this successional sequence
has been carried out in Populus deltoides communities (Wilson 1970; Boggs
1984), it has been assumed that the same sequence applies to Populus
angustifolia communities (Hansen et. al. 1988).
Our study examined the riparian vegetation of the Yellowstone River from
Emigrant, Montana, where Populus angustifolia replaces conifers of the montane
zone - to Sidney, Montana where the river crosses into North Dakota and shortly
thereafter empties into the Missouri. The riparian forests for the first 100 miles of
this stretch are dominated by Populus angustifolia (narrowleaf cottonwood). The
remaining 400 miles of the lower Yellowstone are bordered by Populus deltoides
(Plains cottonwood) communities, in the Northern Great Plains. Salix exigua,
Populus angustifolia, Populus deltoides are all recognized as Montana riparian
dominance types, and have been briefly described (Hansen et. al. 1988). A
more thorough description of the riparian vegetation of the lower Yellowstone,
7
1980-1981, was made by Boggs (1984). Our work characterizes the present
communities, contrasts ungrazed and grazed sites, and compares the lower
Yellowstone today with its status in the early 1980s as described by Boggs
(1984).
Disappearing Resource
In the western United States, riparian ecosystems have been modified by
livestock grazing, agriculture, logging, mining, road construction, flood control
measures and other activities (National Research Council 1995). Nationwide,
approximately 70 – 90% of all riparian areas has been altered significantly
(Hirsch and Segelquist 1978). In the arid West, livestock grazing is an important
factor in this degradation, having affected 80% of riparian ecosystems and
streams (USDI 1994a). The known impacts of grazing on riparian vegetation,
soil properties, streambank stability, fish and wildlife species, hydrology and
stream water quality are summarized in numerous review articles (Kauffman and
Krueger 1984; Chaney et al. 1990; Fleischner 1994; USDI 1994a; Mosely et. al.
1997, among others). The degradation of riparian areas continues, with less than
20% of the West’s potential riparian habitat still in existence (USDI 1994a).
Trimble and Mendel (1995) attribute this continued decline, in part, to a doubling
of the cattle population on Western rangelands in the past half century: from 25.5
million in 1940 to 54.4 million in 1990. Federal land management agencies in the
8
11 western states still permit grazing on 91% of all federal lands (Armour et. al.
1991.)
Grazing Effects
There has been substantial research on effects of grazing on riparian
vegetation. Most of it is focused on the Southwest, the Great Basin and the
Pacific Northwest (Belsky 1999). Studies in the northern Great Plains are rare;
some work has been done in northern Colorado (e.g. Popolizio et. al. 1994;
Sedgwick and Knopf 1991), and in Montana (Marlow et. al. 1989; Ehrhart and
Hansen 1998).
The susceptibility of vegetation to grazing varies greatly among regions
due to adaptation, arising from long association with grazing animals and the
resultant coevolution. Communities of the arid west (the Southwest, Colorado
Plateau and Great Basin) lack such a long history of large, native grazers and
are therefore more susceptible to grazing (Mack and Thompson 1981, Kay 1994,
Berger and Cunningham 1994; Belnap 1997). On the Colorado Plateau,
livestock grazing has had widespread impacts on ecosystem functions (Belnap
1997). On a worldwide basis, the most important factor determining grazing
impacts on plant productivity is the evolutionary history of grazing animals in that
local environment (Milchunas and Lauenroth 1993). In contrast, riparian
herbaceous species of the northern plains (including the Yellowstone) that have
9
been bison grazed are hypothesized to be more grazing resistant. To restate,
studies conducted in southwest, Great Basin and other arid regions of the West
may have little application to riverside vegetation of the Northern Great Plains.
Grazing Effects on Woody Species
As Populus, Salix and Carex species found along the Yellowstone are
common in riparian areas throughout the West, I review the literature describing
grazing and browsing impacts on riparian vegetation. Many riparian studies have
focused on wetter zones, with particular attention to grazing impacts on willows,
sedges and grasses. A few researchers have included cottonwood, aspen and
conifer dominated communities in their work (Powell et. al. 2000).
Biomass and cover of woody riparian species generally decline with cattle
grazing (Kauffman and Krueger 1984). Where grazing is less than five years,
one sees negative impacts on Salix exigua but not necessarily on other woody
species. In a four year study of willows in the eastern Oregon sagebrush-steppe
zone, season long grazing decreased the density of mature Salix exigua, but not
of taller Salix lasiandra. Seedling densities of neither species was reduced by
light to moderate grazing treatments in either the spring or fall (Shaw 1992). On
sites that had not been grazed for thirty years (Sedgwick et. al. 1991,
northeastern Colorado) the biomass of Salix spp. decreased significantly
(P<0.01) with three years of late autumn grazing. Although there was no
significant grazing effect for shrub species combined, the authors noted that a
10
major forage supplement of fallen cottonwood leaves minimized the grazing
treatment originally prescribed. A third study of Populus angustifolia
communities compared the effects of grazing intensity (moderate, light and none)
and season of use (cool, warm and dormant) on cottonwoods in New Mexico.
After two seasons of cattle grazing on cottonwood twigs, browsed trees (not
seedlings) did not differ significantly in either density or height from unbrowsed
trees (Lucas 2004).
In contrast, with thirty years of exclosure in north central Colorado, not
only willow, but all the riparian shrub species increased cover. Willow cover was
8.5 times greater in the pastures rested for 30 years, than in pastures grazed
season long since 1900, and total shrub cover was 5.5 times greater in the
exclosures than the grazed sites. Furthermore, total density of all woody species
was significantly higher in the ungrazed areas (P< 0.02) (Schulz and Leininger
1990). And in Nevada, vegetation of 30 year exclosures was compared to
vegetation of adjacent riparian areas grazed during the summers. Protected
areas had more woody vegetation (P<0.01) and more willow (P<0.03), than the
grazed sites (Ammon and Stacy 1997).
Both long and short-term effects in eastern Oregon, were consistent with
effects of shorter term vs. longer term grazing described above. After three
years of late season grazing, the vegetation of grazed gravel bars had lesser
heights and densities of cottonwood saplings and of willows (Populus trichocarpa
and Salix spp.), than ungrazed gravelbars. The authors observed that the late
11
season grazing was likely retarding succession in these woody-dominated
communities (Kauffman, Krueger and Vavra 1983a). After 11 years at the same
site, with continued late season grazing, the height and density of all woody
species (not just willows and cottonwoods) on gravelbars was reduced by
grazing (Green and Kauffman 1995).
Grazing impacts on woody riparian species other than willow and
cottonwood have been less studied (Powell et. al. 2000). In eastern Oregon,
cattle grazed Ribes spp. hard, often taking more than 100% of current year’s
growth. They also browsed snowberry to a limited extent (Kauffman, Krueger
and Vavra 1983a). In north central Colorado, the woody species that increased
most after cattle grazing exclusion were willow (Salix spp.), shrubby cinquefoil
(Potentilla fructicosa), and aspen (Populus tremuloides), however levels of
increase were insignificant for these species considered individually.
The impact of grazing on woody riparian species varies with season of
use. A survey of the impacts of eleven common cattle grazing systems on willow
communities in central Oregon, concluded that season of use is a critical factor
(Kovalchik and Elmore 1992). Fall grazing was found to be “incompatible with
willow management because of… the switch [from grazing] to browsing” after
herbaceous plants dry out. Light fall grazing didn’t eliminate the impacts on
willow, it just “prolonged the outcome.” Subsequent studies concurred that late
season riparian grazing negatively impacts riparian shrubs (Lamman 1994,
Winward 1994, and Myers and Swanson 1995). With late spring grazing of
12
willow dominated mountain meadows in Idaho, ten years of protection was
imposed to compare the effects of this exclosure with light and moderate grazing.
While willows increased most in the ungrazed exclosures, they also increased in
the late spring light and moderate grazing treatments. There was no heavy
grazing treatment in this study for comparison (Clary 1999).
In Montana all well managed traditional grazing systems – except season
long – could be successfully applied to riparian grazing if the operator monitored
impacts closely, managed their cattle to avoid overgrazing, and encouraged
cattle not to loiter in the riparian areas. It also helped to provide off stream water
for cattle (Ehrhart and Hansen 1998). Note that this study was conducted in the
Northern Great Plains, and may not apply to riparian grazing in arid ecosystems
on the west side of the Rockies.
Mechanisms of Shrub Damage. Cattle grazing damage to willows and
cottonwoods is usually attributed to browsing on younger shrubs and saplings,
rather than from rubbing and bedding on older shrubs (Clary 1989). Skovlin’s
(1984) review concluded that the negative impacts of grazing on riparian trees
and shrubs were “from damage to the regenerative stage of woody plants."
Similarly, Belsky (1999) concluded that the decline in tree and shrub biomass
and cover is due to “browsing by livestock on shrubs and tree saplings when they
are most vulnerable.” In contrast, while Severson and Boldt (1977) agree that
13
browsing is important, they also see rubbing and trampling as important factors in
the Dakotas.
Grazing Effects on Herb Cover/Production
Like shrub cover, graminoid cover and total vegetation cover typically
decrease with long term or heavy grazing. Comparison of constantly grazed
sites in Colorado with areas protected from grazing for 7 – 25 years,
demonstrated that grazing reduced grass, forb and shrub cover, and reduced
shrub height (Crouch 1978). Herbaceous cover was decreased by 42% on
heavily grazed (75% removal) Missouri River sites (Hoffman and Stanley 1978).
In north central Colorado long term grazing reduced total vascular cover, shrub
cover, and graminoid cover, but total forb cover was not significantly affected
(Schulz and Leininger 1990). In riparian mountain meadows in Idaho, ten years
of grazing exclusion significantly decreased forb cover, while there was little
change in the meadows’ total graminoid cover. There was, however, a shift in
species composition as sedges and other late seral species increased
significantly, and exotic (Poa pratensis) cover decreased (Clary 1999). In
contrast, a three year exclosure in north central Colorado showed no change in
relative cover of life forms (forbs, rushes and sedges) but did not test the
possibility that species composition within a life-form may have shifted (Popolizio
et. al. 1994). Belsky’s review (1999), citing 14 studies, concluded that the cover,
biomass and productivity of herbaceous species declines with grazing.
14
The impact of grazing on forb cover is less clear and is undoubtedly
affected by the chemical and physical properties of the plants concerned
(Larcher 2003). Two of papers discussed in the preceding paragraph showed
less forb cover in grazed than ungrazed riparian grassland, one showed no
change and a fourth showed forbs decreased with exclosure.
Grazing Effects on Composition: Natives vs. Exotics
While grazing may not affect the life-form composition of a stand (e.g.
grass vs forb cover), it might modify the species composition within a life-form.
Species composition is likely to shift as grazing sensitive (decreaser) species are
eliminated, increaser species expand their percent cover, and invader species
move in. While species specific responses to grazing are commonly used in the
evaluation of range condition on upland sites (Holechek et. al. 1989), the
phenomenon is poorly documented in riparian sites of the northern plains.
Few riparian studies have examined the effects of grazing on invasion by
non-native species. Significant responses to grazing have only been shown for a
handful of species. In north central Colorado, sites with more than 70 years of
grazing were exclosed and allowed to rest for thirty years. Poa palustris
increased with this release from grazing, having six times the cover in ungrazed
plots as grazed plots. Poa pratensis, on the other hand, decreased 75% with
exclosure. Trifolium repens also decreased significantly with exclosure, to 11%
of its former cover. Carex nebraskensis cover was not significantly different
15
between grazed and exclosed sites, leading the authors to conclude it was
grazing resistant. The possibility that Carex nebraskensis simply couldn’t
recover substantially in the exclosures was not discussed (Schulz and Leininger
1990).
In a three year study in north central Colorado, Taraxacum officianalis,
Trifolium repens and total legumes cover were higher (p < 0.05) on grazed than
ungrazed sites, and Poa pratensis increased with grazing, though not
significantly. Some native species, such as Agropyron trachycaulum and
Potentilla fructicosa, were only found in exclosures; the old exclosures had a
greater proportion of native species than the grazed sites, but none of the
differences in cover were statistically significant (Popolizio et. al. 1994).
In Oregon after 11 years of treatment, there was no significant difference
in percent exotic cover between grazed and exclosed sites on either gravel bar or
cottonwood habitat. However, in the wet meadow exclosures frequencies of the
exotics Phleum pratense and Ranunculus acris declined significantly. In
contrast, Poa pratensis, a widespread exotic, declined significantly in the
cottonwood community with grazing, but also declined significantly with exclosure
in the Ponderosa Pine community (Green and Kauffman 1995).
Of the few studies that have examined species level grazing effects, none
of them found more than four species with significant differences in cover
between treatments within any one riparian plant community (Green and
Kauffman 1995, Popolizio et. al. 1994, Clary 1995, Sedgwick et. al. 1991,
16
Schulz et. al. 1990). Unfortunately, because many grazing studies did not report
species specific vegetation data, they are unable to address this question (Jones
2000). A number of researchers have observed and commented on species
composition changes: either that grazing facilitates the invasion of weedy
species, and/or that late seral, native species increase with exclosure (e.g.
Kauffmann et. al. 1983a; Schultz and Leininger 1990; Clary and Medin 1990;
Green and Kauffmann 1995; Clary 1999).
Grazing Effects on Species Diversity
Grazing can apparently increase or decrease species diversity. The
variance is likely due to differences in initial condition and/or in the treatment
level, with increased diversity due to opening of the stand (reduced competition,
higher soil temperatures) and decreased diversity due to actual consumption of
the plant considered. Thus some papers report increased species diversity in
grazed riparian communities under certain grazing treatments (Dobson 1973;
Green & Kauffmann 1995; Clary 1999; Lucas et. al. 2004). Other papers report
no modification of diversity by grazing in riparian community types (Hoffmann
and Stanley 1978; Kauffmann et. al. 1983b; Green & Kauffmann 1995). One
review concludes that there is a decline in native species diversity with grazing,
but doesn’t address non-native species diversity (Belsky 1999).
Both for the sake of recording species diversity and to completely
characterize community composition, one should record cover estimates for each
17
species present at sites sampled. First, with respect to measuring diversity, a
review of grazing studies conducted in arid upland ecosystems, which found no
statistically significant decrease in vegetation species diversity with grazing in
thirteen studies (P = 0.086), notes, “Although…vegetation diversity [was]
statistically similar between grazed and ungrazed areas, much of this apparent
lack of response to grazing may simply be an artifact of lumping plant species
into broad vegetation categories… The vegetation diversity category [in this
review] would have had more useful implications for range scientists and
managers if it had been possible to include grazing studies that reported
vegetation diversity in terms of numbers of native and non-native species. I urge
future investigators of grazing effects to collect and present vegetation data on a
species-specific basis.” (Jones 2000).
Second, with respect to fully characterizing community composition,
gathering species specific data can also reveal information about rare species,
which is missed by studies that collect and report data by plant life forms only.
For instance, an Australian study that looked at the composition of plant
communities along grazing gradients in upland rangelands, found that many
species were “singletons,” i.e. found only at one site, and that lightly grazed sites
had more uncommon species (Landsberg et. al. 2003). The authors note that
little “is known of the impact of livestock grazing on the less common species that
comprise the bulk of plant diversity.”
18
From these studies, it is apparent that change in species richness is a
limited indicator of grazing effect on community integrity. Species richness,
along, doesn't indicate changes in community composition or relative abundance
of species (cf. Landsberg et. al. 2003). Diversity may increase with grazing, as
the community is opened to exotic species (Dobson 1973), or decline as rare
“decreaser” species disappear with grazing (Landsberg et. al. 2003). Diversity
may remain unchanged if the community is unstressed or if the number of
invading species matches the number of susceptible natives lost (e.g. Kauffman
et. al. 1983a).
Effects on Litter and Bare Ground
As vegetation cover decreases with grazing, litter also declines, probably from
lack of inflow (Belsky 1999, citing five sources). The percent bare ground
increases correspondingly (Clary and Medin 1990; Schulz and Leininger 1990;
Popolizio et. al. 1994; Lucas et. al. 2004 and others).
19
DESCRIPTION OF STUDY AREA
The Yellowstone River is the largest tributary of the Missouri River.
Beginning in the Absaroka Range of northwestern Wyoming, it flows 670 miles
north and then east through Montana, to join the Missouri near Williston, ND. At
its confluence, the Yellowstone’s mean annual discharge is 361 m3/s, about 55
percent of the two rivers’ combined discharge. The longest free-flowing river in
the continental United States, it drains an area of 182,000 km2, of which 48
percent is in Wyoming, 51 percent in Montana and 1 percent in North Dakota
(Figure 1).
The major tributaries of the Yellowstone, from west to east, are the Clark’s
Fork of the Yellowstone, the Bighorn, the Tongue and the Powder Rivers. All
flow north from Wyoming and empty into the Yellowstone in Montana. The upper
Yellowstone, Clark’s Fork and the Bighorn Rivers contribute 86% of the mean
annual flow of the Yellowstone at its mouth. The headwaters for most of the
perennial flow are in the Beartooth, Wind River, Bighorn and Absaroka
Mountains. The reservoir behind Yellowtail Dam on the Big Horn River is the
only major reservoir in the Yellowstone River Basin (Zelt 1999). Streamflow
characteristics of the Yellowstone River are summarized in Table 1, in the
Appendix.
We studied the vegetation along five hundred miles of the Yellowstone
River, beginning 30 river miles north of the Yellowstone’s entrance into Montana,
20
above Emigrant (elevation 1480 m) and ending at the river’s exit into North
Dakota just north of Sidney, Montana (elevation of 575 m.). The riparian gallery
forest of the first 100 miles flows through the “foothills prairie” zone (Kuchler
1964) - and is dominated by Populus angustifolia (narrowleaf cottonwood). For
the next 350 miles the Yellowstone flows predominantly through blue grama,
needlegrass and wheatgrass grassland, changing to wheatgrass-needlegrass
grassland for the final 50 or so miles before it reaches the Missouri River
(Kuchler 1964). The riparian forest (northern floodplain deciduous forest, Kuchler
1964) is dominated by Populus deltoides (Plains cottonwood) for this 400 mile
stretch (Figure 2).
For the basin as a whole, 44% of the potential natural vegetation is
steppe, including the foothills prairie, and the grama-needlegrass-wheatgrass
and wheatgrass-needlegrass grasslands. Invasive exotic species, such as
Russian thistle, are common in some locations. Sagebrush steppe or semidesert
shrub dominates 21% of the basin (out of a potential coverage of 25%); besides
sagebrush, this vegetation commonly includes short grasses and rabbitbrush
(Marston and Anderson 1991). Various types of coniferous forests cover about
19% of the basin, although their potential extent is estimated at 28% (Kuchler
1964). Alpine meadows (3%) are found at high elevations and northern
floodplain deciduous forests (1%) occur in the lowlands, primarily along the
Yellowstone (Zelt 1999). These riparian forests are typically dominated by Plains
21
cottonwood, with willows, boxelder, ash and the non-native Russian Olive being
locally common (Knight 1994; Zelt 1999).
A transition from the Northern Rocky Mountains province into the Great
Plains occurs between the communities of Mission and Springdale, Montana, at
about mile 55 of this study (Fenneman and Johnson 1946). About 45 miles after
this transition, the higher elevation Populus angustifolia (narrowleaf cottonwood)
gives way to the lower elevation Populus deltoides (Plains cottonwood)
(Figure 3).
The Rocky Mountain province gets more precipitation than the lower
elevation Great Plains (Table 2). Average annual precipitation is 200-400 mm in
the plains, 400-600 mm above Livingston, and still higher in the mountainous
unstudied conifer forest zone (Figure 4) (Zelt 1999). In the Great Plains, average
annual precipitation at five weather bureau stations along the river between
Billings and Savage, MT, ranges from 343 mm to 360 mm, averaging 354 mm.
Sidney, MT, at the very downriver end of this study, receives an average of 391
mm (National Climatic Data Center, at http://www5.ncdc.noaa.gov/pubs/
publications.html#CD).
In most of the Yellowstone basin, 40-45% of the annual precipitation falls
during the April – June period. In the upriver Rocky Mountains Province
(Livingston), the highest mean daily precipitation falls in May and June, with a
lesser peak in September. The winter period (December – March) is very dry.
Downriver in the Great Plains Province (Glendive), the maximum mean daily
22
precipitation comes in June, with a lesser peak in late August – early September,
followed by a dry winter period from November through March (Figure 5).
Potential evaporation in the Great Plains province greatly exceeds precipitation,
generally surpassing 900 mm/year and exceeding 1100 mm annually in drier
parts of the Yellowstone River valley (Ostresh et. al. 1990; Marstone and
Anderson 1991, cited in Zelt 1999).
Summer temperatures are slightly cooler and the growing season slightly
shorter in the Rocky Mountain province, compared to the Great Plains. The
maximum daily temperatures occur in late July for both provinces: in Livingston
they average about 29°C, whereas in Glendive they are about 32°C (Figure 5,
Western Regional Climate Center, digital data, 1997, in Zelt 1999). The number
of frost free days at Pine Creek, upriver of Livingston, is 102, based on a 10 year
average while on the lower Yellowstone the ten year average for 11 river
communities is 121 days (Table 2) (http://www5.ncdc.noaa.gov/pubs/
publications.html#CD). The lowest average minimum temperatures come in
early January, with Livingston being milder than Glendive (-9 °C vs. -15 °C
minimums).
Dominant human activities of the Yellowstone River Basin are primarily
livestock production and secondarily irrigated and dryland crop production. In
area, the principal land uses are range (65% of the area) and agriculture (11%).
Forests (20%), mostly at higher elevations, support some timber production on
23
National Forest Service and Reservation lands. Urban or built up areas occupy
only 0.3% of the land base (U.S. Geological Survey 1986, modified in Zelt 1999).
The geology of the Yellowstone River Basin is complex and is well
described by Zelt (1999) (Figure 6). The upriver 75 miles of this study, in which
the Yellowstone flows through the Foothills prairie, is underlain primarily by
Tertiary and Cretaceous instrusive and volcanic rocks, with Quaternary
unconsolidated deposits along some part of the River channel. From Big Timber
(mile 75) downriver, Cretaceous and Tertiary sedimentary rocks underlie the
grasslands of the Great Plains province, with deposits of Quaternary
unconsolidated materials along most of the length of the Yellowstone.
24
METHODS
Overall Sampling Design
To test for grazing effects we sought sites in vegetation/ecosystem types
along the main stem of the Yellowstone, with and without cattle grazing. Most of
our "ungrazed" sites were located at fishing access areas where a low recreation
impact segment represented the ungrazed condition. Matched sites on private
land represented the grazed condition (Figure 7). We then examined vegetation
composition in each of the vegetation types (sandbar, gravelbar, S. exigua, P.
angustifolia, P. deltoides) present at each site. There were cases where we
found a type (e.g. willow thicket) in one but not both treatments. If, in other
cases, we wished to represent two distinct phases of a type (eg cottonwood
forest) we took two samples and treated them as separate samples in t-tests
comparing the grazed and ungrazed treatments. To ensure that the pools of
ungrazed and grazed sites of each vegetation type did not differ from one
another due to average river location, the environmental variables characterizing
each pool were compared.
Vegetation of one zone (eg cottonwood) might contain two (or more)
communities. To minimize this source of variation we ordinated the vegetation of
each zone (Kruskal 1978, see below), and found that willow consisted of one
community while cottonwood (P angustifolia and P deltoides) consisted of two
25
communities (Figures 32 & 35). Heterogeneity of community samples was
further reduced by segregating juvenile vs mature cottonwoods. Thus we
described sandbar, gravelbar, S. exigua, P. angustifolia and P. deltoides
communities separately and tested for grazing effects in each.
Sampling
To characterize ungrazed riparian ecosystems of the Yellowstone River, I
selected 27 locations from Emigrant to Sidney, MT. Twenty of these were at
Montana Fish, Wildlife and Parks fishing access sites (FAS) and the remaining
locations were on similarly protected state or federal lands (Table 3; Figure 7).
The locations chosen were well distributed on the river, free from any significant
cattle grazing (on average for > 20 years) or other human disturbance (e.g.
agriculture, fire, logging, or heavy recreational use). Every Montana FAS on the
Yellowstone River, from Emigrant to Sidney, which met these criteria was
included in the study. Sites above Emigrant were omitted because they contain
conifers and so represent the montane zone, rather than the grassland zone.
To compare grazed and ungrazed conditions I located a similar grazed
stand near each protected site. Eighteen of the grazed locations were on private
ranches, operated by the landowner, one was on a ranch managed for an
absentee owner, and five were on state lands leased for grazing. Only one of the
ranchers who was approached to participate, declined. Ranch selection was
26
based solely on location (close proximity to the fishing access site) and the
presence of cattle grazing, and not on size of operation, management expertise
or the intensity or system of grazing.
Plots were located at representative points in major riparian zones at
each location, for a total of 119. Thirty-two riverside sites included twenty
“gravelbar” and 12 “sandbar” sites. Thirty-two Salix exigua (sandbar willow)
sites appeared slightly inland. And, further inland, I sampled cottonwood forest
including 21 foothill zone Populus angustifolia (narrowleaf cottonwood) stands
and 34 plains Populus deltoides sites. The Salix exigua, Populus angustifolia
and Populus deltoides communities are recognized as Montana riparian
dominance types (Hansen et. al. 1988).
Nine additional stands were sampled but not included in the analysis
because they lacked design requirements. Six of these plots dominated by
Populus acuminata (the hybrid of P. angustifolia and P. deltoides) lacked grazed
site pairs. One site dominated by Salix amygdaloides, and two sites dominated
by Salix rigida were inadequately replicated. The data from these sites are not
reported here. An additional four stands of young cottonwood were sampled and
found to be substantially different from mature cottonwood. The data from the
three ungrazed cottonwood sapling stands (two P acuminata and one P
deltoides) are reported here, but were not averaged with either the vegetation or
the environmental data from the mature cottonwood communities.
27
Community Composition
The vegetation of each stand was characterized by sampling a 2 x 25
meter plot placed in a representative segment. Due to the relatively small size of
sandbars, gravel bars, willow thickets, and ungrazed cottonwood forests there
was usually little room for discretion in plot selection, and when the plot was
located it covered much of the available area. Areas of cottonwood forest were
larger on grazed public and private lands. Where there was evident variability,
two or even three plots were selected to represent the range of variability in age
or understory vegetation. Each 2 x 25 m plot was sampled for species present,
their cover, and their frequency.
Species were identified following Dorn (1984), verified against the
Montana State University herbarium in Bozeman, Montana, and voucher
specimens placed with the MSU Bozeman herbarium. The determination of
which species were non-native was made by consulting the U.S. Department of
Agriculture on-line database (http://plants.usda.gov). For the few species for
which there are both native and non-native varieties in the United States we
assign origin by the sub-species or variety appearing in our area.
To measure frequency (=ubiquity, Daubenmire 1968), presence was
recorded separately for each of the five 5 x 2 meter segments of the plot.
Species occurring outside of the plot, but nearby and in the same vegetation
type, were recorded as present, but “outside”.
28
Cover was estimated for each species. Understory cover was recorded,
by cover class, for herb and low shrub species in a 2 x 2 meter plot at the
beginning of each of five plot segments, i.e. for the 0-2 m., 5-7 m., 10-12 m., 1517 m., and 20-22 m. segments. For taller shrubs, primarily juniper and Russian
olive, cover was measured as the percent of a 25 meter line running through the
center of the transect that intersected each species. Presence or absence of
cottonwood canopy was recorded at twenty-five points, (i.e. at each meter of the
25 meter center-line). Canopy cover was measured with a vertical ‘overhead
periscope’ that viewed a small disc of canopy or sky above the point selected
(Weaver and Dale 1974). Cover was calculated as the percent of points where
“presence” was recorded and, to the extent that both cover and sky appeared in
the field, it is an overestimate.
Ranchers provided information on numbers of cattle in their riparian
pasture, seasons of use and length of use. Detailed records that would have
allowed calculation of stocking rates over the past twenty (or even five) years
were generally not kept. Even when numbers of cattle and season of use could
be described, exact dates cattle were moved and especially pasture sizes (in
acres or hectares) were typically not known. To estimate grazing intensity (over
recent years), cow pat density was recorded for all plots.
This research design: (1) can tell us how riparian vegetation responds to
release from grazing, but not how grazing affects pristine vegetation; (2) can
examine twenty year responses - for instance, shrub responses to grazing vs.
29
exclosure – but may not elucidate long term responses, such as impacts on the
cottonwood life cycle; (3) encompasses the range of variability in riparian sites
along 500 miles of the Yellowstone, as well as a variety of grazing systems,
stocking rates and cattle management approaches. Therefore, any patterns
revealed in vegetation responses to cattle grazing or to recreation site
management will have broad applicability; 5) can quantitatively examine the
responses of individual species to release from grazing, and examine questions
related to plant origin (native vs. exotic); and 6) allows us to make longitudinal
comparisons of riparian vegetation and environmental variables, between
foothills and prairie, and between gravelbar and sandbar substrates as the river
changes from transitional to depositional.
Environmental Sampling
The environment of each site was characterized with indices of climate,
water availability (height above water and depth of soil to gravel), soil texture, soil
salinity (conductivity), CaCO3 and pH, organic matter and nitrogen. Methods are
detailed below.
Climatological Data
Temperature, precipitation and number of frost free days/year data were
all obtained from the National Climatic Data Center, National Oceanic and
30
Atmospheric Administration, U.S. Department of Commerce
(http://www5.ncdc.noaa.gov/pubs/publications.html#CD). We used data for 13
locations along the Yellowstone River (from upstream to downstream):
Livingston south (close to Pine Creek), Livingston, Big Timber, Columbus,
Billings, Huntley, Hysham, Forsyth, Miles City, Terry, Glendive, Savage and
Sidney. These sites reasonably represent all but the first 20 upriver miles of our
study area.
Height Above Water
Height above the river, an index of water availability, was measured once
with a stadia rod and a hand held level in each 2 x 25 m plot. As the water level
in the Yellowstone River gradually dropped over the course of the summer, in
some locations by as much as four feet, and as sites were sampled throughout
the summer months, the “height above water” numbers recorded are only
approximations of the average elevation difference between the soil surface and
the river water surface.
Depth to Gravel
Depth to gravel is used as a second index of water availability; this
assumes that the top of a mature gravel bar has a constant height above stream
water and that when the bar is buried by deposition, that reference height is
preserved. It was measured at the center of each transect by measuring down
31
from the surface through a bore hole, to the underlying gravel layer. The
measurement was straight forward for the sandbar, willow and upriver
cottonwood sites. For some downriver cottonwood sites, however, the depth to
gravel exceeded the 152 cm length of our corer. In these cases, where the
transect was bordered by an exposed, steep river bank, the distance from the
soil surface down to the gravel layer was measured on the river bank instead.
Depths to gravel measured in this way ranged from nearly 2 to 4.5 meters.
Where depth to gravel couldn’t be measured by either method, we assigned the
minimal bank measurement, two meters.
Soil Sampling
Soils of cottonwood, willow and sandbar communities were sampled for
three possible controlling features (soil texture, electrical conductivity, pH) and
two measures of soil development (total nitrogen and organic carbon). Samples
were drawn with an auger from the 0 – 10 cm layer at 20 points, a meter apart,
along the center length of the transect. The samples were mixed, sieved of roots
and stones, air dried (within 12 hours), and then oven dried and analyzed by the
Montana State University soils lab. Soil texture was measured as an index of
water holding capacity, using a modified Bouyoucous Mechanical Analysis (Klute
1986). Both EC and pH measurements were made on a 1:1 slurry (one part soil
to one part water) with standard EC and pH meters (Sparks 1996).
32
Soil samples were also tested for organic carbon and total nitrogen as
indices of soil development. Total carbon and total nitrogen were measured by
combustion analysis, using a LECO Carbon-Nitrogen-Sulfur (CNS) 2000, per the
instrument manufacturer’s instructions. Percent CaCO3 equivalency was
measured by ignition, and was subtracted from total carbon to obtain total
organic carbon (Sparks 1996). That is: Total percent organic carbon =
(total % C) – (% CaCO3 equivalency)(0.12).
Gravel Measurements
As one travels downriver, the river bed composition changes
systematically from coarser to progressively finer sediments (i.e. due to such
‘downstream fining,’ particle sizes decline from boulders at the headwaters,
replaced successively by cobble, gravel, sands, silts and clays, Thorne et. al.
1997). We documented fining on the Yellowstone, by measuring particle sizes
at every gravel beach or sand bar sampled. To characterize particles on gravel
bars we measured rocks at 100 equally spaced points along the center of the
transect. The width of the stone hit by each point, was measured in millimeters.
(Of the three dimensions - depth, width and length – width is the middle
measurement and is therefore the minimum sieve size through which the stone
will pass.) When the point fell on sand, its diameter was recorded as “1 mm.”
Percent sand substrate was calculated as the number of points out of 100 that
fell on sand. This measurement specifies the surface area (%) of substrate
33
available for species that establish in sand, but not on gravel. All 100
measurements were sequenced from lowest to highest value, and the 10th, 25th,
median, 75th and 90th values were recorded as a summary description of that
gravelbar’s substrate/ energy of deposition.
Statistics
Systat (SPSS, Inc 2000) was used to make our statistical analyses, which
included multiple regressions and T- tests. T-tests were run with separate
variance and again with pooled variance; both numbers are given if the values
are not identical (as "sv" and "pv"). Means and standard deviations were
calculated in Excel. Any results significant at p < 0.10 are reported.
To identify communites (sandbar, gravel bar, willow thicket, P angustifolia,
and P deltoides) and assign stands to the correct community type, we used NonMetric Multidimensional Scaling (NMDS) to create ordinations (Kruskal 1978).
PCoA scores were used as initial starting points (Roberts 2005). Sørenson’s
dissimilarity was used to create the dissimilarity matrix (Sørenson 1948). A
tolerance of 1*10-7 was used with 200 iterations to create the final configuration
(e.g. McCune and Grace 2002). No additional dimensions were used if final
stress for the solution was less than 20. Stress is the departure from
monotonicity in the plot of distance in the original n-dimensional space versus
distance in the NMS ordination space (McCune and Grace 2002). Strength of
34
association between environmental variables and NMDS scatter was quanitified
with vector fitting techniques (Oksanen 2005). Vectors were scaled by their
correlation coefficient in NMDS scatterplots.
35
RESULTS
Vegetation and Environment of Ungrazed Communities: Gravel Bars
Distribution
Gravel bars were located at fifteen of the forty-nine study blocks. Because
river deposits become less gravelly downstream (Thorne et. al. 1997), ten of the
fifteen gravelbar sites found were in the upper P angustifolia region (first 100
miles), four were found in the P deltoides (plains region) and one with a high
percentage of sand was found deep in the plains region (mile 492) (Figure 8).
Community Composition
Species presence and cover are reported in Appendix Tables 5 & 6; these
data support calculation of richness and constancy. On average, gravelbars had
17.6 + 12 species, with 46% + 13% of these (7.9) being non-native. Overall, 90
species were found on ungrazed gravelbars, 50% of which (45 spp) were nonnative.
Every ungrazed gravelbar site had seedlings of a native cottonwood,
either P. angustifolia (upstream) or P. deltoides (downstream) (figure 8).
Sites averaged 1.5 shrub species/plot, with six species of shrubs overall –
four natives and two non-natives. Of the shrubs, Salix exigua had by far the
highest constancy (79%), with Salix amygdaloides a distant second (29%). The
36
non-natives Tamarisk chinensis and Elaeagnus angustifolia (Russian olive) both
occurred at low constancies (21% and 7% respectively).
Forb diversity was highest, averaging 9.8 species/plot, with 57% of these
(5.1 species) being non-native. Altogether 57 forb species occurred in the
fourteen ungrazed gravelbars sampled, including 30 native and 27 non-native
species. Only five forbs occurred with more than 40% constancy: the natives
Rumex salicifolius (64%) and Plantago major (43%), and the non-natives
Taraxacum officinale (57%), Melilotus officinalis (57%), and Melilotus alba (43%).
Forty of these 57 species (20 natives and 20 non-natives) were uncommon,
occurring with less than 20% constancy. Twenty six out of these 40 species
were “singletons,” found only at one site out of 14.
Graminoid diversity was intermediate, at 5.4 species per plot on average,
with 36% of these (2.5 species/plot) being non-natives. Overall, 25 species of
graminoids were found, including 16 natives and 9 non-natives. Only the nonnative Poa pratensis (50%), and the natives Poa palustris (43%), and Carex spp.
(43%) had constancies over 40%. Nine of the 16 natives and only two of the
nine non-native species were uncommon, with constancies less than 20%.
Vegetation Cover
Vegetation on gravelbars was sparse, averaging 16% + 9% cover (Table
6). Tree and shrub seedlings comprised most of this cover. In the P angustifolia
(foothill) region, Populus angustifolia (narrowleaf cottonwood) forms the
37
cottonwood forest so its seedlings were found on every site and provided an
average of 5.0% cover. Principal shrubs were Salix exigua (3.4% cover) and
Salix amygdaloides (peachleaf willow), averaging 1.3% cover. In the P deltoides
(plains) region Populus deltoides forms the riparian forest so its seedlings
appeared on every site and provided an average of 0.8% cover. Salix exigua
was the dominant shrub, averaging 7.0% cover. Salix amygdaloides and the
invasive Tamarix chinensis (tamarisk) are less common and sparser, averaging
0.6% and 1.8% cover, respectively.
Total forb cover averaged 3.0% (Table 6). Only the native Rumex
salicifolius (willow dock, 0.4% cover) and two exotic sweetclovers (Melilotus
alba, 1.1% cover, and Melilotus officinalis, 0.3% cover) averaged more than 0.1%
cover. However, 42 other forb species occurred with < 0.1% cover; 17 of these
forbs were non-natives.
Total graminoid cover averaged 3.0% (Table 6). The few species
averaging > 0.1% cover/site included the native Deschampsia cespitosa (0.6%)
and non-natives Agropyron repens (0.8%), Phalaris arundinacea (0.5% cover)
and Alopecurus arundinaceus (0.5%). Twelve other native, and five other nonnative graminoid species occurred on gravel bar sites, averaging < 0.1%
cover/site.
To summarize, on ungrazed gravel bars, a very few species of cottonwood
and willow seedlings dominate in terms of cover (9.3% cover, out of 15.8% cover
present). On the other hand, forbs followed by graminoids have the highest
38
species diversity and the lowest constancy. Of the 82 species of forbs and
graminoids found on ungrazed gravelbars, only eight had constancies of more
than 40%. Non-natives comprise 34% of the cover, 46% of the species richness
per site, and 50% of the richness overall.
Environment
Ecosystems are differentiated by age and environment. Water availability
(e.g. height above water, soil fines, soil organic matter) and the force of flowing
water (e.g. particle size) are important environmental factors.
Gravelbar surfaces averaged 1.4 m (4.7 ft) above water. Thus,
established plants occupying these sites are probably rooted in the water table.
The gravelbar substrate indicates at least seasonally high water flows. It
is a mixture of cobbles, gravel and sand (Table 7). Gravel bar sites averaged
17% (1-35%) sandy area. The percent sand is noteworthy, because species that
don’t establish directly in cobble may still grow in sandy microsites (personal
observation). Populus angustifolia appeared to prefer cobble or gravel while Salix
exigua (sandbar willow), appears to favor sand as a substrate. In figures 8 and
9, photos of a gravel bar at Emigrant West Fishing Access Site, Populus
angustifolia (right) dominates the cobbles deposited on the level top of the
gravelbar while Salix exigua occupies the small sandy bank (left).
The decline in particle size downstream (downstream fining principle) is
illustrated (Table 7, figure 10) with measurements of cobble and gravel size for
39
the gravelbar sites. Of the twelve sites, the five sites with the largest cobbles
occurred within the first 100 miles of the river studied. The ungrazed gravelbar
sites from mile 100 to mile 308 generally had smaller cobbles, and the sites at
mile 308 had the smallest cobbles. The decline in size with distance downriver
was significant for both the 90% and the 75% cobble sizes (p = 0.015 and p =
0.050 respectively). Below mile 308, the newly deposited sediments almost
always formed sandbars (Table 3).
Vegetation & Environment of Ungrazed Communities: Sandbars
Distribution
Sandbars were sampled wherever they occurred in the fishing access
sites or other ungrazed sites. Three sandbar sites were in the Rocky Mountain
province, and five were further downriver in the Great Plains province. Thus
even where the Yellowstone River’s substrate was primarily cobble and gravel,
there were occasional sites where the river flow was slow enough to deposit
sand (figure 11).
Community Composition
Sandbar community composition is described in Table 9. Three
properties, constancy, richness and origin are emphasized below. First, because
so few species occur repeatedly, we note that only 13 native and 13 exotic
40
species are present in more than 30% of the stands: two native trees, one native
and two exotic shrubs, seven native/ten exotic forbs, and three native/one exotic
grass.
Richness is a count of the species in the stand (average richness) or in all
the stands in the type (total richness), without regard for how often they occur or
how much ground they cover. Average species richness for sandbar sites was
25.2 + 8.3 species; primarily in forb and graminoid species (17.1 and 5.5
species/site, respectively, Table 9). Total richness was 105 species. This
included two tree, four shrub, 71 forb and 28 graminoid species.
Sandbars had few species of tree and shrub seedlings. In the upriver P.
angustifolia region (three sites), one site had P. angustifolia seedlings, all had
Salix exigua seedlings, and none had the exotic shrubs. Downstream, in the P.
deltoides (great plains) region, P. deltoides seedlings were present at all five
sites sampled, Tamarisk (exotic) occurred at four sites, Salix exigua at three
sites, and Eleagnus angustifolia (exotic) at only one. Salix amygdaloides (native)
seedlings were present at one upstream and two downstream sites (out of eight
total).
Of the 71 forb species found on sandbars, the maximum constancy was
50%, with ten species in this category. Natives in this group included
Gnaphalium palustre, Rorippa palustris, Amaranthus albus and Xanthium
strumarium; non-natives included Taraxacum officinale (dandelion), Medicago
lupulina (black medic), Thlaspi arvense, and three Chenopods. More than 75%
41
of the forb species (55 out of 71) were found at only one or two of the eight sites;
32 of these species were singletons, found at only one site.
Of the graminoids, Eleocharis palustris had the highest constancy (88%),
with the non-native grasses Phalaris arundinacea, Elymus repens and Bromus
tectorum distant seconds at 38% constancy. Of the 29 graminoid species found,
22 were singletons.
In terms of sandbar plants’ origin, 44% (46 spp) of all species found were
non-native. None of the trees was exotic. Two of the four shrub species were
non-native. Non-natives made up 48% (34 spp.) of the sandbar forbs, and 36%
(10 spp.) of the graminoids. Calculated on a per site basis, non-natives
comprised 43% of the species present (11.3 out of 25.2, on average), including
45% of the forbs (8.6 out of 17.1 species/site) and 44% of the graminoids (2.1 out
of 5.5 species/site).
Vegetation cover
Plant cover on sandbars averaged 39% + 25%. Principal components
were cover of trees (0.3%), shrubs (10%), forbs (16%) and graminoids (12%).
Non-native plants averaged 31% of total plant cover. Exotics (31% + 28%)
varied among sites from 1% - 70% of existing cover (Tables 9 & 10).
Tree seedlings contributed little (0.3%) cover. In the P angustifolia
(foothills) province P angustifolia cover averaged 0.3%, whereas in the plains
region P deltoides seedling cover averaged 0.2%.
42
Shrub cover averaged 10%. Salix exigua was the dominant shrub,
averaging 9% cover. Salix amygdaloides (native) and Tamarix chinensis (exotic)
were also present in small amounts (0.2% and 0.8% cover, respectively).
Forb cover averaged 16%. Polygonum lapathifolium (native, 3% cover)
and Chenopodium glaucum (non-native, 4% cover) were the most prevalent.
Fifteen other forb species averaged between 0.9% and 0.2% cover, with
Polygonum lapathifolium and Equisetum arvense at the top of this list (0.9% and
0.8% cover, respectively).
Graminoid cover averaged 12%. Of the graminoid cover, Eleocharis
palustris (spike rush) averaged 3.0% cover, and Echinochloa crus-galli (exotic,
barnyard grass) – less common but occurring in large patches where it was
found – averaged 3.9% cover.
In sum, sandbars were dominated by herbaceous plants. Forbs and
graminoids together provide 28.3% cover, trees and shrubs only 10.3% cover.
Of the 25.1 species/site (average richness), 22.6 are non-woody. In terms of
species diversity, forbs and graminoids were 99 out of 105 species occurring on
sandbars. The great majority of these herbaceous species occurred with low
constancy.
Non-natives are a substantial component of this plant community:
comprising 31% of the plant cover, 43% of the average species richness and
44% of the species richness across all sites (Tables 9 & 10).
43
Environment
The environmental variables for all eight ungrazed sandbar sites were
averaged and are presented in Appendix Table 8. Surfaces of ungrazed sandbar
sites averaged 1.4 meters (4.6 feet) above water.
The sandiness of soils - 72% sand, 21% silt and 7% clay - is consistent
with deposit at moderate flow rates, slower than gravel, but higher than silt.
CaCO3 increased with distance downriver. The quantity was negligible or too
small to measure for the Populus angustifolia (upriver) zone, but averaged 3.0
percent equivalency for the downriver sites in the Populus deltoides zone.
Organic carbon was 0.37%, and total nitrogen was 0.023%, consistent with the
short time since deposit available for their accumulation (cf, Boggs 1984).
Conductivity averaged 0.37 mmhos/cm, with no upriver vs. downriver difference.
Vegetation and Environment of Ungrazed Communities:
__________Salix exigua (Sandbar Willow)___________
Distribution
Willow communities (figure 12) usually occupy a zone between
sandbar/gravelbar and cottonwood forest. Despite environments ranging from
cool/mesic to warm/dry on soils ranging from gravelly to fine textured, our
ordinations did not segregate willow communities in the P angustifolia (foothill)
region from those in the P deltoides (plains) region (figure 30). They included 22
44
ungrazed sandbar willow stands, 11 from the Populus angustifolia (foothills) zone
and 11 from the Populus deltoides (plains) zone.
Community Composition
Species richness for this community was 22.0 + 7.3 species per site, with
averages of 0.6 tree species, 4.7 shrub, 11.5 forb and 5.1 graminoid species
(Table 11). Non-natives comprised 46% + 13% (9.6 + 2.9 spp) of the average
species richness. The range in both numbers of species (13 – 40) and in percent
non-native species per site (21% - 73%) was substantial.
Total richness for this vegetation type was 132 species, including 3 trees,
21 shrubs, 75 forbs and 33 graminoids. 33% of the species found overall (43 out
of 132) were non-natives. Percentages of forb and graminoid species (59%,
58%) that were non-natives, were higher than those of shrub species (10%).
Most of the woody plant diversity of the Salix community was due to native
shrubs. In the 22 Salix exigua sites sampled (11 upriver, 11 downriver), there
were 3 native tree species, 19 native shrub species and only 3 non-native shrub
species. While P angustifolia was essentially absent in willow thickets in its
(foothill) zone, Populus deltoides seedlings were 82% constant in its (plains)
range. Salix exigua had 100% constancy, as its presence defined this vegetation
type. Four other native shrubs had high (>30%) constancy across both zones:
Salix amygdaloides (50%), Ribes aureum (45%), Cornus stolonifera (45%) and
Rosa sayi/R. woodsii (36%). Two non-natives were sometimes present, but only
45
in the prairie zone: Tamarix chinensis (55% constancy) and Elaeagnus
angustifolia (36%).
Average forb richness, 11.5 species, was more than half non-native (6.4
spp). Across all Salix exigua sites, there were 75 forb species, of which 39% (29
species) were non-native. Five non-native forbs had high (> 40%) constancies:
Cirsium arvense (Canada thistle, 91%), Taraxacum officinale (dandelion, 68%),
Sonchus sp. (sow thistle, 55%), Cynoglossum officinale (houndstongue, 41%)
and Solanum dulcamara (nightshade, 41%). Only one native forb was as
common: Solidago gigantea, with 50% constancy.
Average graminoid richness (5.1 species) was also more than half nonnative (2.7 species/site), while overall richness (33 species) was 33% non-native
(11 species). Common exotics were Phalaris arundinacea (73% constancy), Poa
pratensis (68%) and Elymus repens (59%). Agrostis stolonifera (36%) was the
most constant native graminoid. (Note: A. stolonifera is considered native by
USDA and by Flora of the Pacific Northwest, but non-native by University of
Montana's invader database (Table 4).)
Note that the average per site richness of both non-native forbs and
graminoids (>50% in both cases) is higher than their overall cross site richness
(39% and 33%, respectively). For this to be true, non-natives must have higher
average constancy than natives in willow thickets. This may be an indication of
the competitive ability of exotics. Indeed, there were eight non-native herbs with
> 40% constancy, but only one such native in willow thickets.
46
Vegetation Cover
Plant cover, summed across all strata, in ungrazed Salix exigua (sandbar
willow) communities averaged 111.4% (Table 12). In the upriver zone willow
thickets, Populus angustifolia seedlings were virtually absent from the community
while in the downstream zone, Populus deltoides seedlings averaged 1.4%
cover.
Salix exigua dominated this shrub community with an average cover of
51% in the P angustifolia (foothills) and 50% in the P deltoides (plains) zones.
Companion shrub species provided another 14% cover. Native mesic species
included Salix amygdaloides (peachleaf willow) with 6% cover throughout, Ribes
aureum (golden current) with 1% cover throughout and Cornus stolonifera (red
osier dogwood, 1.6%). Dogwood was common in foothills zone willow
communities where it averaged 3.3% cover, but while it can be important in
downriver stands and can appear in mature cottonwood communities, it was
absent from all our plains zone willow stands. More xeric native shrubs included
Symphoricarpos occidentalis (western snowberry) with 1.1% cover throughout
and Rosa sayi/Rosa woodsii (wild rose) with < 1% cover. Two non-native shrubs
absent from upriver willow sites, Elaeagnus angustifolia (Russian olive) and
Tamarix chinensis (tamarisk), appeared in downriver willow stands with average
covers of 2.4% and 0.5%, respectively.
47
Forb species collectively averaged 17% cover in the Salix exigua zone.
Although there was great diversity of native forb species, collectively they
provided < 4% cover, and no single species averaged > 1% cover. Most of the
forb cover (>13% out of 17%) consisted of non-native species, primarily Cirsium
arvense (Canada thistle), at 7% average cover. Other non-natives, with average
cover >1%, were Melilotus officinalis, Melilotus alba, Solanum dulcamara
(climbing nightshade) and Cynoglossum officinale (hound’s tongue).
Graminoid cover averaged 31%. As with forb cover, most of the
graminoid cover (25% out of 31%) was composed of non-native species. The
most important exotic graminoid was Phalaris arundinacea (reed canary grass),
which averaged 20% cover. Poa pratensis averaged 2.5% cover. While native
graminoids included rushes (Juncus spp), sedges (Carex spp) and grasses, only
Agrostis stolonifera (red top), Poa palustris (fowl bluegrass), and Carex sp., had
>1% cover.
Overall, the Salix exigua vegetation type is dominated by sandbar willow
and other native shrub species (51% cover out of a total 114%). Although there
is a great diversity of native forb and graminoid species in sandbar willow
thickets, the less diverse non-native forbs and graminoids appear to be more
successful: they provide 38% cover compared to natives’ 10%, and include more
species with high (>40%) constancy than natives do (8 non-natives vs. one
native) (Tables 11 & 12).
48
Upriver (foothill) and downriver (plains) willow sites had similar species
richness (20 + 7 spp vs. 24 + 7 spp). While cover of non-natives was higher in
downriver sites, standard deviations associated with these figures were large
(32% + 24% vs. 47% + 23%, Table 11). Thus the difference was not statistically
significant (p = 0.152 s.v./p.v.). The two most notable differences between
upriver and downriver sites are that plains willow sites included both cottonwood
(P. deltoides) seedlings (82% constant) and the invasive shrubs Russian olive
and tamarisk (55% and 36% constancy). At upriver sites, P. angustifolia
seedlings were a negligible presence (18% constancy) and the invasive shrubs
were absent.
Environment
The environmental data for the 22 ungrazed Salix exigua sites were
summarized for the vegetation type (Table 8). To compare the environment of
Salix exigua thickets between the foothills and the plains zones, averages were
also calculated for each zone (Table 8, "upriver" and "downriver").
Seven differences between the upriver and the downriver Salix exigua
sites are noted. Indices of river water availability vary downstream. As one
moves downriver, the height of the river banks increases (Table 8). Soil surfaces
in the willow ecosystem of the foothills (P. angustifolia) zone averaged 1.8 m (5.9
ft) above water, while those of the downriver prairie (P. deltoides) zone averaged
2.3 m (7.6 ft) above water. The height of flood waters (i.e. current deposition) is
49
suggested by depth to gravel and surface textures. Upriver willow zone soil
surfaces are elevated with respect to the gravel layer (116 vs. 106 cm.), contain
slightly less sand, and contain slightly more silt than their downriver counterparts.
Organic matter content (C and/or N) might rise with site productivity,
length of the productive period (stand age), or organic matter deposition. The
soils of foothill willow sites have more organic carbon (1.35% vs. 0.62%) and
more total nitrogen (0.090% vs. 0.039%) than their downriver counterparts (Table
8), however these differences are not quite statistically significant (for C: p =
0.12; for N: p = 0.13).
Finally, soil CaCO3 is very low at upriver willow study sites (0.4 percent
equivalency average) and gradually increases downriver (3.2 average) (Table 8).
Soil pH follows suit; it is slightly more acid at upriver than downriver sites (pH 7.9
vs 8.2) (Table 8). Soil electrical conductivity (a leaching/water rise indicator) was
relatively high in this vegetation type (0.51 mmhos/cm, average) and while it was
variable among sites (0.18 – 1.51 mmhos) we saw no longitudinal pattern
downstream (Table 8).
Vegetation & Environment of Ungrazed Communities:
___Populus angustifolia (Narrowleaf Cottonwood)___
Distribution
Narrowleaf cottonwood forms mature forests with shrub understories at
some distance from the river (figures 13 & 16). Populus angustifolia forest is a
50
major riparian dominance type of the foothills zone, central Montana,
predominantly east of the Continental Divide (Hansen 1988). Our stands were
found on upriver sites, from above Emigrant MT to Reed Point, MT. Eight sites
supported mature cottonwood trees (figure 13). The largest trees of these stands,
characterized by averaging the largest three, had average diameters at breast
height of 56 cm, with a range of 35 – 81 cm. Two additional sites (UCN2 and
UEN3) were sampled to represent younger sapling forests. In both of these,
average maximum diameters were 5 cm.
Near Reed Point, Populus angustifolia disappears, to give Populus
deltoides full dominance of downriver riparian forests. A hybrid, P. acuminata
(lanceleaf cottonwood), is formed where the ranges of the species meet, at least
on the Yellowstone. Occasional sites dominated by P. acuminata, and with
either P. angustifolia or P. deltoides, were found between Livingston (river mile
46) and Reed Point (river mile 103). We do not describe ungrazed P acuminata
forest because P acuminata forests were only found on grazed lands.
Community Composition
Average species richness for the Populus angustifolia community was
19.8 + 5.9 species per site, with averages of 1.1 trees, 5.3 shrubs, 8.9 forbs and
4.5 graminoids. Non-natives comprised 34% + 8% of average species richness
(Table 13).
51
The woody vegetation was comprised exclusively of Populus angustifolia
and native shrubs. Rosa sp., although not dominant, had the greatest constancy
(88%), followed by Symphoricarpos occidentalis (75% constancy). Ribes
aureum, Juniperus scopulorum, Rhus trilobata, Ribes setosum and Cornus
stolonifera all had constancies of 50% or more. Salix exigua was found at only
one out of eight sites.
Average forb richness, 9 species, was equally split between natives (5
spp) and non-natives (4 spp). Across all Populus angustifolia sites, 39 forb
species were found, of which 46% (18 species) were non-native. The most
common natives were Smilacina stellata (100% constancy), Solidago gigantea
(75%), and Glycyrriza lepidota (38%). The non-natives with highest constancy
were: Cirsium arvense (Canada thistle, 88%), Taraxacum officinale (dandelion,
75%), Arctium minus (common burdock, 38%) and Tanacetum vulgare (tansy,
38%).
Average graminoid richness was predominantly non-native, with 3.0 of 4.5
species exotic. Across all sites, 14 different graminoid species were found, of
which half were non-native. The non-native graminoids with the most cover also
had the highest constancies: Poa pratensis (100% constancy), Phalaris
arundinacea (63%) and Bromus inermis (50%). The native graminoids were less
common; only Elymus trachycaulus (slender wheatgrass, 38%) approached 40%
constancy.
52
Both sapling Populus angustifolia stands had a monospecific tree layer.
Though essentially absent in mature stands, Salix exigua was still present in
both. Native shrubs had not yet entered. The herbaceous layer was primarily
non-native grasses (24% cover, 3.5 spp/site), forb cover was less than 1%, and
herbaceous diversity at 9.5 species/site was 66% of that in mature forests (13.4
spp).
Vegetation Cover
The mature P. angustifolia community had substantial tree, shrub and
herbaceous canopy layers, with 168% + 26% total cover (Table 14).
Tree cover averaged 88% in the eight mature stands. With the exception
of one site with Fraxinus pennsylvanica (green ash, 12%), the tree cover was
entirely Populus angustifolia.
The shrub layer was also entirely native and averaged 47% cover in
mature forests. Components included Symphoricarpos occidentalis (snowberry,
15%), Cornus stolonifera (red osier dogwood, 10%), Juniperus scopulorum
(Rocky Mountain juniper, 10%) and Rosa sayi/R. woodsii (5%). Seven other
native shrub species occurred, each with less than 2% average cover. The nonnatives, Russian olive and tamarisk did not occur in the foothills zone. Willows,
remnant from earlier seral stages, were rare; Salix exigua was not found and
Salix amygdaloides only occurred in one of eight stands.
53
Forb cover averaged 13% in narrowleaf cottonwood forests, with half (7%)
native and half (6%) non-native. The most important exotic was the noxious and
ubiquitous Cirsium arvense (Canada thistle, http://invader.dbs.umt.edu, 4%
cover). The most constant natives also had the most cover: Smilacina stellata
(starry false Solomon’s seal, 2.3% cover), Glycyrrhiza lepidota (wild licorice,
2.2%) and Solidago gigantea (late goldenrod, 1.2%).
Graminoid cover, averaging 20%, was mostly non-native (16%). Exotics
Phalaris arundinacea, Poa pratensis (Kentucky bluegrass) and Bromus inermis
(smooth brome) each averaged 5% cover. The most important native, Agrostis
stolonifera, had 3% average cover; Juncus and Carex species so common in
adjacent willow stands were uncommon and present only in small amounts (<
0.5%).
In sum, the cover of Populus angustifolia communities is composed
primarily of native trees and shrubs (88% and 47% cover, respectively). Overall,
the Populus angustifolia community was composed of monospecific stands of
narrowleaf cottonwood trees, with a shrub layer characterized by a suite of eight
commonly occurring native species. Of these, Symphoricarpos occidentalis is
the most dominant, although Juniperus scopulorum and Cornus stolonifera are
important where they occur. The herbaceous layer is dominated by the nonnative grasses Phalaris arundinacea, Poa pratensis and Bromus inermis, and the
invasive forb Cirsium arvense. The native forbs Smilacina stellata and Solidago
gigantea are very common, but provide little cover. There are no common native
54
grasses. Non-native forbs and grasses (22% cover), provide more cover than
native forbs and graminoids (11% cover).
The two sapling sites sampled were notably similar to one another. Tree
canopy, exclusively P. angustifolia, was less than in mature forests (57% vs. 88%
cover), there were no forest shrubs, and while forb cover averaged less than
1%, exotic grasses were well established in both (3% and 45% cover). One
stand had remnant willow cover, linking it back to the precursor community.
Environment
Because narrowleaf cottonwood only grows at higher elevations (>1170
m. = 3835 ft.), it had relatively high rainfall (>400 mm/year), July temperatures
with an average maximum daily temperature about 29°C, and a comparatively
short frost-free season (102 days at Pine Creek) (Table 2). Throughout its range,
the river substrate is primarily cobble and gravel.
Of the four upriver (foothill) communities, cottonwood forests are furthest
above water. Surfaces average 2.4 m (7.7 ft) above the river (Table 8).
Increases in fine material (36% sand, 49% silt, 15% clay), relative to that in
adjacent willow (51%/38%/11%) and sandbar (72%, 21%, 7%) sites, also
demonstrate the rising soil surface. Depth to gravel averaged 111 + 45 cm,
comparable to upriver Salix exigua sites, which averaged 116 + 50 cm. This
suggests that these two communities co-exist, rather than being in a seral
relationship to one another.
55
Four other soil properties were examined. Soil organic carbon (2.80%)
and total percent nitrogen (0.168%), indicators of duration of production (= stand
age), and/or productivity, were higher than in adjacent younger communities and
in communities downriver. Soil CaCO3 was negligible (0.4 percent equivalency),
and pH was correspondingly low (7.8). Soil electrical conductivity averaged 0.45
+0.22 mmhos/cm.
Vegetation & Environment of Ungrazed Populus deltoides
_________Communities (Plains Cottonwood)__________
Distribution
Populus deltoides occupies the driest riparian sites in the plains
(downriver) region, i.e. from central through eastern regions (Hansen 1988).
Our sites ranged from Reed Point (river mile 103) to Sidney (river mile 510)
(Tables 15 & 16). Seventeen mature, ungrazed Populus deltoides stands were
sampled (figure 13). Maximum diameters (DBH, largest three trees) averaged 60
cm, with a range from 38 to 112 cm. One younger stand, site U2P, was
sampled to demonstrate a cottonwood sapling community.
Community Composition
Average species richness for Plains cottonwood forests was 19.4 + 6.6
species per site, with averages of 1.5 trees, 5.8 shrubs, 7.9 forbs and 4.2
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graminoids. Non-natives comprised 43% + 11% (8.3 + 3.4 spp) of the average
richness (Table 15).
Populus deltoides, since it defined this community, had 100% constancy.
Green ash, the only other tree species present, occurred as seedlings at 47% of
the sites sampled, and at one site as a young tree.
Of the twenty shrub species present, eighteen were native. Natives
included Symphoricarpos occidentalis, which had 59% constancy, followed by
Rosa spp. (53%), Vitis riparia (wild grape, 47%), Clematis ligusticifolia (white
virgin’s bower, 41%) and Toxicodendron rydbergii (poison ivy, 41%). Elaeagnus
angustifolia, was the most common exotic shrub, with 76% constancy (Table 15).
47 forb species occurred in mature Plains cottonwood stands, with 22 of
these (47%) being non-native. Only four of these species had constancies
greater than 40%. They were the natives Apocynum sibiricum (hemp dogbane,
59%) and Smilacina stellata (41%) and the non-natives Taraxacum officinale
(65%) and Medicago lupulina (black medic, 59%) (Table 15).
Sixteen grass species were found overall, of which half (8 spp) were nonnative. The exotics were common: Poa pratensis (76% constant), Bromus
inermis (76%), Elymus repens (59%) and Phalaris arundinacea (53%). The
natives were much less common, none having a constancy greater than 24%
(Table 15).
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Vegetation Cover
Summing across layers, ungrazed plains cottonwood communities
averaged 156% cover, with trees contributing 81% cover, shrubs 41%, forbs 5%
and grasses 29% (Table 16).
The tree canopy was exclusively Populus deltoides. Downriver, green ash
seedlings became more common, averaging about 0.5% cover/site below mile
250 (Hysham, MT). Green ash saplings were found at only one site (U1P),
where they provided 15% cover.
The shrub layer was well developed, averaging 41% cover. The primary
shrub cover is provided by two species not found upriver, non-native Elaeagnus
angustifolia (Russian olive, 15% cover) and native Toxicodendron rydbergii
(poison ivy, 8% cover). The natives Symphoricarpos occidentalis (5% cover),
Juniperus occidentalis (5%), Rosa sp. (1.5%), and Cornus stolonifera (1.1%) are
present.
Forb cover was only 5% total, evenly divided between native and nonnative species. Only the exotics Arctium minus and Solanum dulcamara
averaged more than 0.5% cover.
Grass is more important with 29% cover, primarily non-native grasses
(25%). Of the exotics, Bromus inermis is most extensive (15% cover) followed
by Poa pratensis (4%), Elymus repens (4%) and Phalaris arundinacea (1.7%).
The native Elymus trachycaulus provided 1.7% cover, on average.
58
In sum, in Populus deltoides stands the tree canopy layer is composed
solely of Plains cottonwood. A great diversity of native shrub species (18 spp.)
were found overall, collectively providing 26% cover per site, but the dominant
shrub in terms of both cover (15%) and constancy (76%) was the exotic Russian
olive. Forbs were the most diverse life form (47 spp overall), but the least
important community component in terms of cover (5%). Grasses were less
diverse than shrubs (16 spp. overall), with four non-natives dominating in terms
of both cover and constancy: Bromus inermis, Poa pratensis, Elymus repens and
Phalaris arundinacea. Non-natives account for 43% of the species richness per
site, 38% of the overall richness for this vegetation type, and 28% of the cover
(Tables 15 & 16).
The one sapling community sampled resembled the P. angustifolia sapling
communities in lacking the native shrub layer. Elaeagnus angustifolia was
already establishing, but with less than 1% cover. Euphorbia esula (leafy
spurge) provided most of the 11% forb cover. While grass cover was only 1%,
the four most common non-native grasses were already present (Table 16).
Environment
Precipitation in Plains cottonwood communities is low (averaging 354 mm
precipitation/year) and summers are warm. July daily maximums in Glendive
peak at about 32°C. The frost-free season averages 121 days, 2.5 weeks longer
than at Pine Creek, in the Populus angustifolia zone (Table 2). Their range on
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the Yellowstone reaches from the predominantly cobble substrate at Reed Point,
to the sands and silts at the river's confluence with the Missouri.
Populus deltoides communities grow on alluvial terraces further above the
river level (4.4 m, = 14.3 ft) on average, and with greater depth to gravel (157 cm
average) than younger bar and willow stands (Table 8). This estimate is low
because when the depth to gravel exceeded152 cm, the length of our auger (at 7
of 17 sites), we used a conservative estimate of depth (2 m.) This was based on
depths to gravel measured on nearby river banks (see Methods).
Soil organic carbon (1.88% + 0.93%) was significantly less (p= 0.069
s.v./p = 0.043 p.v.) and total nitrogen (0.125% + 0.066%) was slightly less (p =
0.131 s.v./p = 0.132 p.v.) than the values for Populus angustifolia communities,
but substantially higher than the sandbar and willow community soils (Table 8).
Soil texture for both cottonwood communities was loamy (41% sand, 39% silt
and 20% clay for P. deltoides soils), with less sand and more silt than the willow
and sandbar soils.
Percent CaCO3 equivalency increased significantly with distance
downstream (squared multiple r = 0.75; p = 0.000). P. deltoides soils averaged
3.4% CaCO3 equivalency, with a pH of 8.1 (Table 8), both higher than in P
angustifolia stands. Electrical conductivity averaged 0.48 +0.23 mmhos/cm,
comparable to P. angustifolia soils.
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DISCUSSION
To determine how grazing management impacts plant communities of the
Yellowstone we describe these communities and their functioning in absence of
grazing. First, we describe the vegetation of the ungrazed sites, both in the
lateral (seral) sequence from bar through willow to cottonwood forest and
longitudinally from foothills downriver to the plains. Next we compare plant
species richness, constancy and cover among the ungrazed types as further
characterization. Finally lateral and longitudinal gradients in environmental
factors will be described as possible causal agents. Our understanding of
ungrazed vegetation will provide a basis for the following evaluation of grazing
effects on riparian plant communities.
Ungrazed Vegetation
Composition
The botanical composition, both presence and quantity, of the five
communities is recorded in tables 5 - 6 and 9 - 16.
Summary Description
We consistently saw three vegetation zones along the entire Yellowstone
River’s length: bar communities at the water’s edge, a willow thicket immediately
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inland, and a cottonwood forest further inland. Similar zones were recorded by
Boggs (1984) and Hansen et al (1988).
Bar communities were either sand or cobble depending on source (gravel
available in foothills) and energy of deposit (cobbles remaining in high energy
areas). Upstream (foothill) bars were primarily cobble and supported a sparse
(16+9%) cover dominated by cottonwood seedlings, with willow seedlings, forbs,
and grass in lesser and roughly equal quantities. Downstream (plains) sites (and
occasional upstream bars) were primarily sand and supported a dense cover (39
+ 25%) with few cottonwood seedlings (0.3% cover), more shrubs (10%), forbs
(16%), and grasses (12%).
The thicket community was surprisingly consistent across foothill and
plains zones. The canopy is willow (51% cover), with hydric shrubs (Salix
amygdaloides, Ribes spp, Cornus stolonifera) (14%). The understory is
dominated by forbs (17%) and grasses (31%). Cottonwood seedlings were
almost nonexistent in the foothills zone (one site, with 0.001% cover) and
common, but sparse in the plains (82% constancy, 1.4% cover). Tamarix and
Elaeagnus angustifolia are invading the willows downstream.
The physiognomy of the cottonwood community was also surprisingly
consistent. The canopy is dominated by cottonwood with 88% cover of P
angustifolia in the foothills, and 81% of P deltoides in the plains. A layer of mesic
shrubs covers 47% (foothills) - 41% (plains). Four species provide most of the
shrub cover upstream (Symphoricarpos 15%, Juniperus 10%, Cornus 10%, and
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Rosa 5% cover), but only a quarter of the downstream shrub cover. In the plains
their dominance is shared by two heat loving shrubs: Toxicodendron (8%) that
has always had a role, and exotic Elaeagnus (15%). Russian olive has recently
invaded and appears to be adding cover to or replacing cover of its shrub
associates, thereby modifying the composition of this community (Table 16;
Boggs 1984).
An herbaceous ground layer provides an average cover of 33%. Grasses
dominate the ground layer increasingly as one moves from the foothills (13%
forbs/20% grasses) to the plains (5%/29%), perhaps because the plains climate
is drier and grasses tend to be more drought tolerant than forbs.
Species Richness and Constancy Compared
________Across Vegetation Types________
Diversity (Species Richness) in
the Yellowstone River Riparian
The species present in a stand, its richness, include its dominant, more-orless regular associates, and accidentals. We discuss diversity of the
Yellowstone riparian zone as a means to characterize the system, to compare
richness of component communities, and as a basis for comparing grazed and
ungrazed examples of each type.
We consider three commonly used measures of diversity – total richness
of the ecosystem, total richness of component community types and average
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richness of sites in each community type. First, we found a total of 281 species
in our 132 plots spread among five community types and distributed over 500
miles of the Yellowstone River (Tables 3 & 4). Since some vegetation types
were not sampled, the actual value is certainly greater.
Second, richness of our five component plant communities, ranged from
68 to 132 species per community type (Table 17). At the river’s edge, 105
species total occurred on sandbars, sampled with eight plots over 486 miles. On
harsher riverside sites, gravelbars, 90 different species were found at 14 plots
over 302 river miles. Just inland the Salix exigua type had both the highest
species count, and also the greatest sampling effort: 132 species at 22 plots over
486 river miles (table 17). Furthest inland, the Populus angustifolia type of the
foothills had 68 different species, found at eight plots distributed over 91 river
miles. And in the plains the Populus deltoides community included 85 species, at
13 plots over 407 river miles. All plots were 25 m. x 2 m. Diversity differences
among the types cannot be rigorously compared because they varied in sample
size [species number increases with sample size (Keammerer 1975)], miles of
river sampled (another aspect of sample size), and inherent community
differences. Populus angustifolia, sampled at only eight sites over just 100 miles
of river, had the lowest overall richness, and only a 3.4-fold difference between
overall (68 species) and per site richness (19.8 spp). In contrast ungrazed Salix
exigua communities, sampled with 22 sites distributed over 486 river miles had
132 species, six times the per site average of 22 species.
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Third, because many species occurred with low frequencies, the average
per site richness of each of our five communities was much lower than the overall
richness for that community. However, because the sample was of a constant
size (2 x 25 m) richness can be rigorously compared across our five community
types (cf. Gregory et al 1991). Of the vegetation types surveyed riverside,
sandbars (25.2 + 8.3 species) and the harsher gravelbars (17.6 + 12 species)
(Table 17) had the highest and lowest average richness/site. Salix exigua
thickets were second highest, with 22 + 7.3 species per site. And Populus
angustifolia and P deltoides forests had comparable richness, 19.8 + 5.9 and
19.0 + 6.6 species/site, respectively.
We compare our results with those of two parallel studies both because all
describe riparian vegetation and because they illustrate the desirability, in making
comparisons, of using the same methods. First, in a more humid (Oregon)
location Green and Kauffman (1995) found 55 species/site on gravelbars (vs. our
18) and 40 species/site in the adjacent Populus trichocarpa community (vs. 19 20 for our cottonwoods). At each site, they sampled 2.4 m2 total (thirteen 25 cm2
plots in each of three stands) for herbs, and 10 m2 (ten 1 m2 plots) for shrubs,
over three kilometers of river. How much of their ‘greater richness’ is due to the
difference in their sampling strategy, one which covers less area/site, but
samples a “site” that is more broadly distributed than our single 50 m2 plots?
Without common sampling strategies, the apparent differences are intriguing, but
not conclusive.
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Second, on the lower Yellowstone Boggs (1984), also sampling smaller
plots distributed over a larger area, found fewer species (Table 29). The
discrepancy is likely due in part to their sampling method being 60 step-points vs.
ours being 2 x 25 m. transects. It is probably due also to the addition of nonnative species to these communities since 1980. In 1980, the average percent
non-native species across the three community types sampled was 20.0%; by
2001 it was 44.0% (Table 29).
Lateral Variation in Species Richness. We hypothesized that richness
would fall from the river’s edge through willow thicket to mature cottonwood
forest due to decreasing seed rain (wash), diminishing site disturbance and water
availability, and increasing competition from established plants (Cf. Green and
Kauffman 1985; Kauffman et. al. 1985; Fleischner 1994; Ohmart 1996; Nilsson
and Svedmark 2002). Richness did fall from sandbars (25.2 + 8.3) through
thicket (22.0 + 7.3) to forest (19 + 6). The exception was found on gravel bars
(17.6 + 12), where there is little suitable surface and that is unstable. However,
these differences in richness are statistically insignificant, except that the most
diverse vegetation type (sandbars) is marginally significantly richer than the least
diverse (gravelbars) (p = 0.10 s.v./0.14 p.v.).
The base richness of sandbars (25 spp/site) is set by three qualities of the
environment: their proximity to floodwaters, their openness, and their proximity
to the water table. Proximity to flood waters, at an average 1.4 meters above
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river level, facilitates delivery of seed. Fresh unoccupied deposits provide a noncompetitive environment: with only an average 39% plant cover on sandbars,
germinants are more likely to survive than those seeded into denser willow
thicket or cottonwood forest. Proximity to the water table provides germinants
with plentiful water that, because it retreats with falling river levels, must be
pursued with vigorous rooting.
Gravelbars are similar to sandbars in their openness and proximity to
floodwaters and the water table. However, gravelbars may have a lower
richness than sandbars for four reasons. 1) They are on average further
upstream, so collect seed from a smaller area of watershed (seed shed) than
sandbars, which is likely to reduce seed diversity. 2) Seed outwash is higher,
both because water flows are stronger and because there is less simultaneous
deposit of silt. 3) Previously established plants are more likely to be removed by
strong flow over gravel bars than by weaker flows over sandbars. 4) The rooting
medium of sandbars supports better establishment than does the cobble of
gravel bars. We regularly observed better establishment on patches of sand
forming microsites in large gravelbars (Figure 15).
Willow thickets were second to sandbars in species richness (22 spp/site),
and more diverse than cottonwood stands. We hypothesized that the following
six factors are involved. 1) Flood deposited seed probably arrives in quantities
similar to sand/gravel bar sites. 2) Flood exported seed is probably less in
thickets than sand and gravel bars, due to more shrub and herb cover, and more
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flotsam. 3) Due to their greater age, willow thickets have more years to have
collected establishing species, either annual and/or perennial. 4) Willow
communities are typically long, narrow thickets lying in the ecotone between the
riverbanks and the cottonwood forests, and therefore share species with each.
Most sites included along their edges a few species more characteristic of each
of these neighboring communities. We hypothesize that of the vegetation types
studied, willows have the greatest mix of obligate wetland, facultative wetland
and upland species due to their ecotone location and high edge effect. 5)
Compared to cottonwood stands, willow thickets have greater access to
subsurface water. 6) Compared to sand/gravel bar sites, establishment of new
species is reduced by existing plants; both shading and lateral root competition
are more intense in willow thickets.
Cottonwood forests have lower richness (19 - 20 spp/site) than either
sandbar or willow thickets/communities. We pose five conflicting mechanisms.
1) Since flooding is both less likely and less violent, seed input and seed and
seedling export are relatively low. 2) Reduced flooding and a deeper water table
remove the guarantee of an annual germination/establishment window. 3)
Closed vegetation greatly inhibits the establishment of small seeded plants like
Populus or Salix. 4) Presence of bird perches and mammal cover increases the
input of ‘berry’ seeds and burs. These inputs are evidenced by the appearance
of berry-bearing shrubs (e.g. Symphoricarpos, Toxicodendron, Cornus,
Juniperus, Rosa, Elaeagnus) and burs (e.g. Arctium, Glycyrrhiza, Cynoglossum).
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5) Older vegetation has had more time to accumulate plants adapted to the
climate, soils, and the cottonwood canopy.
Longitudinal Variation in Species Richness. We expect species richness
to increase downstream for three reasons. Increase in watershed (seed shed)
areas will increase the diversity of seeds delivered from upstream sites. Increase
in flood violence will increase the availability of establishment sites, but through
recurrent floods, may reduce their longer term safety. The climate warms
downriver (Table 2), thus providing suitable sites for warm-adapted species.
While this may not affect the native plant richness, it will likely increase the
diversity of exotics. For instance, non-native shrubs are absent in the foothills,
but common in the plains (i.e. Russian olive and tamarisk).
Exotic diversity increases with warmth because our exotic flora is
frequently from the Mediterranean and the Middle East, than from northern
Europe. We cannot test this well in riverside sites because substrates differ
between gravel bars of the foothills and sandbars of the plains. We can test for
this by comparing non-native richness in willow thickets of foothills (8.8 + 3.4 spp)
and plains (10.4+ 2.2 spp), and in cottonwood forests of foothills (6.9 + 2.9 spp)
and plains (8.3 + 3.4 spp). The difference is less than imagined, and not
significant.
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Species Constancy Along the Yellowstone
The large differences between overall community richness and average
site richness imply that many species occur with low constancy. This has also
been found in other riparian ecosystems (Gregory et al 1991).
Some species, the defining ones (eg Salix and Populus), are always
present (100% constant), some are usually present, and some are rarely present,
i.e. ‘accidentals’. One can test for patterns regarding the distribution of the low
constancy (accidental) species on longitudinal (up- vs downriver) and age/lateral
(perpendicular distance) river gradients. To do so we will define accidentals as
those species with less than 20% constancy, i.e. occur only once or twice.
We hypothesized that the percent low constancy species will fall laterally
among vegetation types from the river to the forest. In other words, we expected
constancy to increase from river’s edge through cottonwood forest for two
reasons. First, the likelihood of accidental delivery and establishment of a poorly
adapted flood-borne plant is more likely at a moist streamside than in the
adjacent cottonwood forest. Second, while plants well adapted to an
environment arrive as “accidentals”, the probability of arrival rises with time, so
communities of older, relatively stable sites (e.g. cottonwood) eventually collect
all their members, i.e. have higher average constancy than communities of
ephemeral sites (e.g. sandbars and gravelbars).
Contrary to our hypothesis, inconstants were similar in bar (gravel 59%,
sand 53%) and cottonwood (narrowleaf 44%, Plains 62%), but high in willow
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(78%). We asked whether the excess of low constancy species in S. exigua
thickets was native or non-native (Table 18). Low constancy species were most
likely to be non-native on gravelbars (43%, or 23/54) and on sandbars (41%, or
23/46), less likely to be exotic in P. angustifolia (37%, or 11/30) and in P.
deltoides stands (38%, or 20/53), and least likely to be exotic in willow thickets
(27%, or 28/102). The difference for willow thickets was thus primarily due to
large numbers of low constancy native shrubs, forbs, and to a lesser extent
graminoids (table 18). Something about willow thickets favors incidental, low
constancy species. One possibility is the ecotone location of willow thickets,
between forests and river edge communities. Another might be the “intermediate
disturbance hypothesis” applies: willows, with intermediate flood frequencies,
could be more species rich than rarely or frequently flooded sites. This has been
shown for riparian ecosystems in southeast Alaska (Pollock et. al. 1998). Note
that in this study, sandbars had higher richness/site than willow thickets, but the
difference was not significant.
We had originally hypothesized that natives and non-natives would be
equally likely to occur at low constancies. This analysis showed that in all five
vegetation types surveyed, the percent of non-native low constancy species was
equal to or less than the percent of all species in that vegetation type that were
non-native. In other words, natives are more likely to be accidental than nonnatives (Table 18). And accidentals (native or non-native) are more likely to be
71
forbs than grasses, shrubs or trees, which may be due to the greater proportion
of forbs in the flora.
Native/Exotic Comparison Across Vegetation Types
The factors contributing to high species richness in riparian ecosystems
may also make them more invasible by non-native species (Pysek and Prach
1994; Hood and Naiman 2000). The high level of disturbance continually creates
open sites for pioneer or invasive species, and the river corridor acts as a
distribution network for propagules (Fox and Fox 1986; Crawley 1987; Planty
Tabacchi et. al. 1996). For the Yellowstone (and many other rivers), the long
history of human habitation, agriculture, ranching, industry and recreation along
the river likely adds both to disturbance levels and to production/distribution of
non-native propagules.
The percent exotic plant species present has been studied in riparian
ecosystems, on country wide, river and drainage scales. In all of Great Britain,
the percent of non-natives is 13 – 39% for riparian habitats. Invasive species
came primarily from the Asteraceae, Poaceae and Fabaceae families. Nonnatives represented 24% of the 1396 species found along the Adour River in
southwest France, and 30% of 851 species for the MacKenzie River in the
central Cascades, Oregon (Planty Tabacchi et. al. 1996). On a smaller scale,
also in the Cascades, non-natives comprised 24% of the 148 species in the Hob
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drainage, and 28% of the 200 species for the Dungeness drainage (Planty
Tabacchi et. al. 1996). For four South African rivers, exotics accounted for 20%
to 30% of the total species richness (Hood and Naiman 2000). In an extensive
analysis of data from 184 sites (upland and riparian), Lonsdale (1999) found a
positive relationship between native and non-native species diversity. High
diversity riparian communities are thought to be more invasible than low diversity,
resource poor communities, because their relatively rich resources are made
available to invading species via disturbance (Stohlgren et. al. 1998, 1999, in
Masters and Sheley 2001).
In my study, of the total 207 species found in ungrazed sites across the
five major vegetation types, 33% were non-native (Table 17). Despite my
examination of little disturbed sites, this exotic percentage is "high" relative to
American, French or South African river studies mentioned above. The
Yellowstone's non-native species came primarily from five plant families:
Poaceae (18 spp.), Asteraceae (11), Brassicaceae (11), Chenopodiaceae (7)
and Fabaceae (7) (Table 19).
Analyzing the data simply in terms of percent non-native species for the
entire riparian ecosystem probably does not sharply represent what is happening
on the ground. To more completely depict the situation, some researchers have
subdivided riparian ecosystems into specific vegetation types (gravelbars,
shrubs, forests), and have found that the more frequently flooded, earlier seral
stages in riparian ecosystems have higher percentages (Planty-Tabacchi et al.
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1996; Hood and Naiman 2000) or higher numbers (DeFerrari and Naiman 1994)
of exotic plants. They suggest that flooding denudes lower lying areas, thereby
increasing their invasibility (Hood and Naiman 2000). Although young
communities had more alien species than older ones, even the mature
communities appeared to be invasible (Planty-Tabacchi et al. 1996).
We had hypothesized that non-native richness would fall laterally among
the vegetation types, with bar communities being the most invaded. In this study,
breaking the data down by vegetation type reveals that while the percent nonnative is still 33% for the willow community, it’s higher for the other types.
Populus angustifolia and P. deltoides contained 37% and 38% non-native
species, respectively, whereas sandbars and gravelbars were higher yet, at 44%
and 50% respectively. Using these figures, the earliest seral stages of the
Yellowstone are apparently the most invasible, as has been found for other
rivers.
If the non-native richness/site numbers are considered, non-native
richness falls from sandbars (11.3 species/site) to willows (9.6 spp/site) and
further to cottonwoods (6.9 spp/site for P. angustifolia; 8.3 spp/site for P.
deltoides. Gravelbars, the least rich vegetation type overall, had 7.9 non-native
species/site.
There is a discrepancy here between the “33% exotic species” for the
Yellowstone’s riparian vegetation as a whole, and the higher percentages of
exotics in the individual vegetation types. This could only be happening if the
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non-native species are occurring across a wider variety of vegetation types, on
average, than the native species. The non-natives that are most widespread in
riparian areas may have an adaptive edge over natives because they are better
disperses, and/or perhaps have a greater tolerance for resource variability.
Species that can survive in multiple riparian vegetation types, ranging from sunny
to shady, frequently to rarely flooded, sand to loam - arguably have a great
advantage in this very spatially and temporally heterogenous ecosystem. One
study of five of the most widespread invasives of riparian ecosystems in North
America found that all the species studied “show a high degree of morphological
plasticity in response to hydrologic change” (Galatowitsch et. al. 1999). In other
words, these successful invasives are particularly adapted to change in water
availability, as is found from river edge to cottonwood forest, and from high to low
river flows throughout the year.
To test this, I compared constancy of natives vs non-natives, across the
five vegetation types surveyed (Table 20). Native shrubs were found across 2.3
plant communities on average, while non-native shrub species averaged 3.0.
However, as there were only three non-native shrub species, this statistic isn’t
significant. For forbs and graminoids, natives had significantly more limited
ranges. Native forb species occurred, on average, in 2.1 different plant
communities, while non-native forbs averaged 2.6 communities (p = 0.03).
Native graminoids occurred in 1.8 different vegetation types on average, while
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non-native graminoids were more adaptable, occurring in 3.0 different
communities on average (p = 0.02).
Non-native graminoids as a group were more successful in invading
riparian ecosystems (as measured by percent cover) than non-native forbs
(Table 17). While the two groups start out with equivalent percent cover in
gravelbars (1.4% and 1.9%, respectively) and in sandbars (5.2% and 6.5%
respectively), in willows non-native grasses contribute 24.6% cover, while nonnative forbs only 13.3% on average. In P angustifolia stands, exotic grasses
comprise 16.4% cover while exotic forbs only 6.3%. Populus deltoides stands
have 25% cover of non-native grasses, but only 2.2% cover of non-native forbs.
Another test of this hypothesis that non-natives have either a greater
ability to disperse and/or a greater tolerance of resource variability, is to compare
numbers and characteristics of species that occur across all five vegetation
types. The majority of these species are either woody or noxious. Seven native
species were found in all five vegetation types. These included the woody
species which germinate on fresh alluvial deposits and mature through
succession (Salix exigua and S amygdaloides), a grass (Agrostis stolonifera),
and four broadly occuring native forbs. Among forbs, Glycyrrhiza lepidota (wild
licorice) is notable because it increases with grazing and is considered noxious
by many of the ranchers who participated in this study. The Populus species
might be included because they each occur across all seral stages from river
edge to forest, but were only found in four of five vegetation types since they do
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not co-occur (i.e. P. angustifolia isn’t found in P. deltoides forests, nor vice versa,
except for hybridization where their ranges meet).
The twelve non-natives that occurred in all five communities are
ubiquitous or noxious. The forbs are Cirsium arvense (Canada thistle),
Euphorbia esula (leafy spurge), Melilotus officinalis (yellow sweet clover),
Tanacetum vulgare (tansy), Taraxacum officinale (dandelion), Verbascum
thapsus (mullein), and Sonchus asper (marsh sow thistle). Grasses Poa
pratensis, Phalaris arundinacea, Elymus repens, Bromus inermis and Alopecurus
arundinaceus had equally broad ranges of tolerance.
This information is potentially useful in weed management, as it tells us
which species are particularly in need of control on sandbars and gravelbars
and/or in upland fields - before they invade the adjoining willow and cottonwood
communities.
Evolution of Lower Yellowstone Riparian Communities 1980-2000
Boggs (1984) described riparian succession in Montana as beginning with
the establishment of willow and cottonwood seedlings on sandbars and
gravelbars, followed by willow-cottonwood thickets, which with willow die off are
succeeded by young cottonwood forests, and eventually maturing cottonwood
forests (at about 3, 7, 34 and 92 years, respectively). Shrubs appear under the
cottonwoods, but when the cottonwoods die, the understory shrubland
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community is replaced by grasslands (Boggs 1984) (Figure 16, showing
progression from gravelbar to P. angustifolia forest).
We had hypothesized that there would be no significant changes in the
plains riparian communities between 1980-1981 (Boggs 1984) and 2001 (our
data). However, dynamics of the present (2001) suggest changes in early seral
communities, leading to a dramatic change in future mature riparian forests. A
graph of our foothills data (Populus angustifolia sere), Figure 17) is constructed
paralleling Boggs' (1984) plot of his observations on the plains: gravelbar, willow
and cottonwood replace each other serially. A graph of our plains data (Figure
18) shows similar dynamics. Salix exigua cover rishes and falls, and is replaced
by other shrub species that increase as the cottonwood forests mature.
Herbaceous cover peaks in the willow community, with graminoids retaining
more cover in the P. deltoides community (29% cover) than in the P. angustifolia
community (20%), and forbs more cover in the P. angustifolia community than in
the plains (13% vs. 5%).
Populus deltoides cover, on the other hand, is low on sandbars and in
willow thickets. This cottonwood's apparent failure to reproduce forbodes drastic
change in the forest zone. The following paragraphs detail changes in the plains
sere.
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Gravelbars
On gravelbars in the plains, Salix exigua is the dominant woody species
(7% cover), with P. deltoides seedlings contributing only 0.3% cover on average,
and nowhere doing well. I don't know whether P. deltoides has declined on
gravelbars, or has never established well on this substrate. The invasive
Tamarix chinensis established well at all three gravelbar sites below river mile
250, averaging > 3% cover. This is notable because twenty years ago, no
tamarisk was recorded in any of more than 50 transects of riparian sites along
the lower Yellowstone (Boggs 1984).
Sandbars
Sandbar vegetation in the plains zone appears to have changed
substantially in the past twenty years. In 1980-81 (Boggs 1984), P. deltoides
seedlings dominated river edge sites along the lower Yellowstone, averaging
21% cover, with Salix exigua seedlings providing another 5% cover. Forbs (5%
cover) and grasses (2% cover) were less important, with three Polygonaceae
species and the exotic Echinochloe crusgalli (barnyard grass) providing most of
the herbaceous cover. Neither tamarisk nor Russian olive was found at any of
the nine river edge sites sampled. Non-native species accounted for 25% of the
species richness across all sites, but only 10.9% of the total cover (Boggs 1984),
i.e. 4.2% cover out of the total plant community cover of 38.4%.
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In 2001 sandbars had essentially the same total cover (38.6%), but the
composition changed dramatically. In the Populus deltoides zone, their
seedlings have been reduced from dominance at 21% cover, to negligible at only
0.3% cover. Not one of the five plains sites, even the most remote, had
cottonwood seedlings with 1% or more cover. Salix exigua had an increased
presence at 8% cover, and the exotic tamarisk, absent in the early 1980s, is now
present at 80% constancy and 1.5% average cover.
Herbaceous cover and percent non-native cover have increased at
sandbar sites since the 1980s. Forbs have tripled to 16% cover and graminoids
are up from 2% to 12% cover. The presence of non-natives has increased
dramatically: from 25% to 44% of the total species richness, and from 11% to
almost a third (31%) of the total cover (12.5% out of 38.6%) (Tables 9, 10 and
17). While it's possible the difference in sampling methods could account for
some of this increase in absolute cover, the ratios of non-native/total species
present shouldn't be affected by the use of different methods.
Both River Edge Communities
In sum, sandbar willow thrived on both ungrazed gravelbar and sandbar
sites, in both 1980 and 2001. Populus deltoides' cover dropped from 21% (1980)
to less than 1% cover (2001) over the past twenty years. Downriver in the P.
deltoides zone, the exotic shrub tamarisk has gone from no recorded presence,
to being widely established on both sand and gravelbars.
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Is it possible that 1980 & 1981 were just good years for P. deltoides, when
the earlier field work was done - while 2000-2001 just happened to be a poor
year due to differences in river conditions and spring floods? This question can
be addressed by looking at the next successional community, the thickets, which
represent a longer time period.
Salix exigua Thickets
In the early 80s on the lower Yellowstone, S. exigua and P. deltoides
saplings were co-dominants in thickets, each averaging 30% cover across the
eight stands sampled (Boggs 1984). The cottonwood saplings were averaging
two meters high, so they had not yet overtopped the willows. Herbaceous plants
provided just 25% cover, and were predominantly native. There were two
common non-natives: Elymus repens (quackgrass, 3% cover) and Melilotus
officinalis (sweet clover, 1% cover). Phalaris arundinacea was found only at one
site, at < 1% cover, and Cirsium arvense only averaged 0.5% cover and 38%
constancy. Neither tamarisk nor Russian olive were present. Non-natives
comprised 27% of the species richness/site, and approximately 9% of the total
cover (Boggs 1984).
In 2001, P. deltoides is no longer a co-dominant in willow thickets; it now
comprises only about 1% cover. Today, sandbar willow is dominant in thickets at
ungrazed sites all along the Yellowstone, which average 50% S. exigua and 6%
S amygdaloides cover (Tables 9 & 10). Sandbar willow is two to four meters
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high, with peachleaf willow overtopping it where it occurs (figure 12). Shrub
species that were absent twenty years ago are establishing in the willows, but all
at less than 2% average cover apiece. The new shrubs include both exotics and
natives. The exotics tamarisk and Elaeagnus (Russian olive) now occur in plains
willow thickets with constancies of 55% and 36%, respectively. Native shrub
species that form the understory in mature cottonwood forests also appear; these
include Cornus stolonifera (Red osier dogwood), Ribes aureum (golden currant),
and Rosa sp. (wild rose), with constancies of 45%, 45% and 36% respectively.
Consistent with the disappearance of our overstory dominant, this
community has simultaneously developed an understory of exotic forbs and
herbs, not present twenty years ago. Phalaris arundinacea (reed canary grass,
20% cover), Cirsium arvense (Canada thistle, 7% cover), and other less
extensive non-natives have increased from 9% to 39% of the total cover, and
from 27% to 46% of the overall species richness of this vegetation type (Table
17).
What has happened to the P deltoides saplings, once co-dominants with
Salix exigua? We don’t recollect ever seeing stands of 2-3 meter high P
deltoides, and suspect that this tree has not reproduced well for at least ten
years. The young Populus deltoides stand we did sample (site U2P, Tables 15 &
16) was composed of older, fairly tall trees, with a dominant tree cover, and
minimal shrub understory (as they were some twenty years ago, Boggs 1984). A
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survey of the age distribution of Plains cottonwood stands (adjusted for floodplain
turnover rate), not undertaken in this study, would be valuable.
Mature Populus deltoides Community.
Twenty years ago, P. deltoides saplings in willow thickets grew to overtop
the willows, to form mature cottonwood forests with a shrub understory
dominated by natives Rosa woodsii (12% cover), Toxicodendron rydbergii
(poison ivy, 13% cover) and Symphoricarpos occidentalis (snowberry, 6% cover).
The native grasses Elymus canadensis (Canadian wild rye, 6% cover) and
Muhlenbergia racemosa (muhly, 5% cover) were more extensive than the nonnatives Poa sp. (bluegrass, 4%) and Bromus inermis (smooth brome, 2%).
Parthenocissus quinqefolia (Virginia creeper, 1%), Vitis riparia (wild grape, 4%)
and Elymus smithii (= Agropyron smithii, western wheatgrass, 1%) - all natives were the only other species averaging more than 1% cover. Forbs were sparse
and uncommon, with none averaging more than 0.5% cover in mature forests
(Boggs 1984). Collectively, non-natives comprised 22% of the overall species
richness, but only 3.9% of the total cover present.
It appears that the downriver willow thickets we sampled will not develop
into cottonwood forests, for the simple reason that the cottonwood saplings are
almost completely missing (Tables 11 & 12). Instead the willows are likely to be
replaced by the largest shrub species now establishing in these thickets, Russian
olive. This replacement may have been occurring in eastern Montana for
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decades. In 1980-81, Russian olive was found in half of the mature cottonwood
transects between Glendive to Sidney, but never with ≥ 1% cover (Boggs 1984).
In 1988, Russian olive was described as a "minor, but locally abundant" riparian
dominance type in eastern Montana, which had already "become a management
concern" for both private and public land managers (Hansen 1988). Its "potential
to displace native riparian vegetation" and interfere with both ranching and
farming operations was recognized (Hansen 1988). In 2001, Russian olive
occurred in 75% of cottonwood forest transects from Reed Point to Sidney - all
400 miles of the lower Yellowstone - and averaged 15% cover. This almost
certainly underestimates the extent of its presence on the landscape scale, as
transects were run only in P. deltoides communities. Russian olive dominated
stands existed, but weren’t sampled.
Russian olive is altering the composition of cottonwood communities, as it
also establishes under mature Populus deltoides trees, as well as in willow
thickets. In twenty years Russian olive has gone from minimal presence (never >
1%) (Boggs 1984) to being the dominant shrub, with 15% average cover and
75% constancy (p = 0.003 s.v./p = 0.055 p.v.). That it may outcompete the
natives Rosa sp. and Vitis riparia, is suggested by their decline from 12% to
1.5%, and from 4% to 1% average cover, respectively (p = 0.02 s.v./0.00 p.v. and
p = 0.17 s.v./0.01 p.v.). Natives Toxicodendron rydbergii (8% cover) and
Symphoricarpos occidentalis (5% cover) are both still present, and forbs remain
sparse (5% cover, collectively). Non-native grass cover has increased
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substantially at the expense of native grasses. The exotic Bromus inermis has
expanded from 2% to 15% average cover, and now dominates the herbaceous
layer (p = 0.10 s.v./0.01 p.v.). Non-native Poa pratensis (Kentucky bluegrass)
remains at 4% average cover, while exotic Elymus repens has gone from rare
(one site out of six) to 59% constancy and 4% average cover (not significant, p =
0.400 s.v./0.122 p.v.) Native Elymus canadensis has been reduced from 6% to
1% average cover (p = 0.040 s.v./0.046 p.v.) and Muhlenbergia racemosa went
from 5% average cover to almost none (p = 0.03 s.v./0.00 p.v.).
Collectively, non-natives have increased from 22% to 43% of the species
richness, and have increased their percent of the total cover from 4% to 28%. It
is important to note that this change in community composition over the past
twenty years has happened while these sites have been exclosed from grazing.
Grazing Effects
We compare vegetation and physical environment on grazed and
ungrazed sites in five vegetation/environmental types below. Grazing might
affect vegetation either through selective consumption, through trampling
sensitivity, or indirectly through soil compaction (Dale and Weaver 1974).
Selective consumption might reduce a favored species or increase a dis-favored
species by removing the competition of the favored species. Changes in
vegetation might affect the physical environment (e.g. soil texture, soil moisture)
85
by reducing infiltration and increasing surface runoff, evaporation and erosion
(Mosley et. al. 1997). We tested for other environmental correlates to reduce
the likelihood of assignment of cause to non-causal correlates. Thus we
measured grazing effects on cover (by stratum), richness, exotic presence, and
environmental quality.
Gravelbar Communities
14 ungrazed gravelbar sites and 6 grazed gravelbars were sampled. Nine
of the ungrazed and five of the grazed sites were in the foothills zone; the
remaining gravelbars were in the plains (Table 3). The ordination (Figure 30) did
not segregate foothills from plains gravelbars, so they are combined in the
analysis. On three of six grazed sites, cover of cow pats averaged 0.2% cover,
and woody seedlings were grazed. On the other three “grazed” sites cattle were
present in pastures abutting the gravelly river edge and clearly had free access
to the gravelbars, but the bars showed no signs of cattle use (no pats, no grazed
seedlings). On “ungrazed” sites, cattle had no access and there were no cow
pats on them.
Dominance. The most noticeable effects of grazing are visible cattle
browsing of both cottonwood and willow seedlings, a reduction in average shrub
cover (from 6.4% to 2.5%) and significant increases in three forbs, non-natives
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Euphorbia esula and Chenopodium botrys, and the native Equisetum variegatum
(Table 21, and Tables 17 vs. 26).
P angustifolia seedlings thrived in some locations, but did poorly in others,
making it difficult to assess the impacts of grazing. On unrecreated, ungrazed
sites, five transects averaged 8.8% cover. At the grazed sites, two locations with
sign (GIA and GKA) had browsed P angustifolia seedlings with an average cover
of 6.2%, while two transects at a fourth location had neither cottonwood seedling
cover nor evidence of grazing. The single “grazed” site where P angustifolia
seedlings were ungrazed, had no evidence of cattle presence (no cow pats, no
other grazing, no hoof prints). The sixth site (G2B), in the plains, had cow pats
and the P deltoides seedlings were grazed. In short, wherever there were both
cattle and cottonwood seedlings, the seedlings were browsed.
Shrub cover may be reduced at grazed gravelbar sites. Salix exigua
declined from 4.7 to 2.2% cover, Salix amygdaloides declined from 1.1 to 0.2%
cover, and Tamarisk chinensis declined from 0.7 to 0.0% cover. We observed
substantial grazing on willow seedlings at all three sites with cow pats. Although
the declines in cover were not statistically significant (p = 0.13, separate
variance/p = 0.29 pooled variance), it seems likely that the very visible decline in
biomass (not measured) would be significant. (On sandbars, where S exigua
has 9.0% cover on ungrazed sites, the decline in cover with grazing is
significant.)
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The overall forb cover increased slightly with grazing from 3% to 4%.
Three forb species increased significantly: two non-natives Euphorbia esula
(leafy spurge, p = 0.08), Chenopodium botrys (Jerusalem oak goosefoot, p =
0.05) and the native horsetail, Equisetum variegatum (p = 0.028). Graminoid
cover was 3% on both ungrazed and grazed sites. Phalaris arundinacea was
eliminated with grazing on gravelbars.
Richness. Overall species richness/site was similar: 17.6 + 12 for
ungrazed and 23.7 + 11.5 for grazed gravelbars (p = 0.31). Nor did grazed and
ungrazed gravelbars differ significantly for any specific life form. Although
richness across all sites was slightly higher for ungrazed (90 spp vs. 74 spp), this
is likely due to the fact that we sampled twice as many ungrazed (14) as grazed
(6 ) gravelbars (Table 21, and Tables 17 vs. 26).
Exotic Presence. The percent of non-native species/site was also similar:
46% + 13% for ungrazed sites, and 39% + 8% for grazed sites. Percent of cover
contributed by non-natives was 34% + 35% for ungrazed sites, and 37% + 27%
for grazed sites. The variation in cover values, i.e. the contribution of other
factors, prevents detection of any hypothesized difference. To restate, cover of
non-natives was very variable, ranging from 1% - 100% of total cover on the 14
ungrazed sites, and from 12% - 76% of total cover on six grazed sites (Table 21,
and Tables 17 vs. 26).
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Environment. There were no statistically significant differences in the
environment of the ungrazed sites vs. the grazed sites (Table 27).
Sandbar Communities
Eight ungrazed sandbars were sampled, but only four samples on grazed
lands were found. Cow pats averaged 0.3% cover on grazed sites, but were
absent from ungrazed sites.
Dominance. Grazed sandbars had substantially less cover (18.6% +
14.1%) than ungrazed sandbars (38.6% + 25.0%) (p = 0.105 s.v./0.17 p.v.)
(Table 22, and Tables 17 vs. 26).
Forebodingly, cottonwood reproduction was slight on all sandbars for both
species, never reaching 2% cover for any location. Cottonwood seedlings were
heavily cattle grazed at the three ranch sites where they occurred (P angustifolia
at GGB, P deltoides at G2B and G2B2). The decline in total vegetation cover
with grazing is due primarily to loss of shrub cover, down from 10.0% cover to
only 0.3% cover (p = 0.06 s.v./p = 0.15 p.v.). Salix exigua was most affected,
declining from 9.0% to 0.3% cover (p = 0.08 s.v./p = 0.20 p.v.). This willow was
moderately to severely grazed at all grazed sites, as was Salix amygdaloides at
the one site it occurred. Tamarisk cover was reduced from 0.8% average cover
on ungrazed sites to 0% cover at the single grazed site in its range (G2B/G2B2).
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This site was heavily trampled by cattle. We never saw evidence of tamarisk
being grazed by cattle or beaver.
Although both forb and graminoid cover decreased with grazing (16% to
11%, and 12% to 6%, respectively), neither reduction was significant. On both
ungrazed and grazed sites, the exotic Chenopodium glaucum was the most
prevalent herb.
Richness. Ungrazed sites had insignificantly higher richness than grazed
sites (25 + 8 vs. 20 + 14), with most of this difference being due to ungrazed sites
having higher forb richness/site (17.1 vs. 11.5).
Exotics. The importance of exotic species varied greatly among sandbar
sites, as it did among gravelbar sites, i.e. the percent of total cover contributed by
non-natives on sandbars varied from 1% to 70%. Exotics comprised 37% + 31%
of the cover on ungrazed sites compared with 26% + 24% on grazed sites
(P=0.55 s.v./0.57 p.v.) Whether this is random variation, or whether there is a
correlation with recreational, grazing and/or other human impacts, is
undetermined (Table 22, and Tables 17 vs. 26).
Environment. We attribute the differences between grazed/ungrazed sites
to cattle treatment, because grazing and trampling were seen at all four grazed
sandbar sites, and because alternate factors varied little. Cowpie cover
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averaged 0.3% on grazed sites, and was absent from ungrazed sites. Ungrazed
and grazed sandbar sites were not statistically different from one another with
respect to most measured environmental variables that could contribute to
differences in plant communities, i.e. mile on river, height above water, depth to
gravel, pH, electrical conductivity and CaCO3. Ungrazed and grazed sites
differed significantly in soil clay content (7% vs. 11%; p = 0.068 p.v./0.165 s.v.),
and organic carbon (0.38% vs 0.62%; p = 0.051 p.v./0.099 s.v.). While these
differences are correlated with cattle use we doubt that they are caused by or
influenced by cattle (Table 27).
Salix exigua (Sandbar willow) Thickets/Communities
Twenty-two ungrazed sites and ten grazed Salix exigua thickets were
located. Of the grazed sites, seven were in the P angustifolia (foothills) zone,
and three in the P deltoides (plains) zone.
Dominance. Grazed willow vegetation had significantly less cover (89%)
than ungrazed transects (111%, p = 0.056 s.v./p = 0.041 p.v.) (Table 23, and
Tables 17 vs. 26).
Cottonwoods were a minor component of Salix exigua communities.
Populus angustifolia is rare in willow thickets, and was only found in two of 18
willow stands (one grazed, one ungrazed) in its range. At the grazed site, mature
narrowleaf cottonwoods overhung the transect, and the seedlings below were
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grazed with the willows. P deltoides reproduction was similar throughout its
zone, with 1.5% cover on ungrazed sites and 1.0% cover on grazed sites.
Grazing reduced Salix exigua cover from 51% to 31% (p = 0.0005 s.v./p =
0.0016 p.v.) (Table 23). Constant grazing also prevented Salix exigua height
from reaching its potential; heights were 2 - 4 meters on ungrazed sites, and less
than one meter for some willows on six out of ten grazed sites (Figures 12 & 29).
These six heavily grazed sites averaged 1.1% cow pat cover. At two other lightly
grazed sites (cow pat cover 0.03%), willows were less reduced in height (from 3
to 2 m.). At one location, the willows were so tall the cattle could only hedge
them. At the tenth location, there was no indication of recent grazing of any
plants, and no cow pats in the transect.
Loss of S exigua is understated if grazing has eliminated willow thickets
from some grazed lands. Willows were sampled wherever they occurred in our
24 ungrazed locations, and 21 grazed ranches. The facts that 75% of the
ungrazed sites, but only 48% of the grazed sites had willows, and that the
protected sites were much smaller (averaging 42 acres) than the grazed sites
suggests that willow may have been grazed out at some sites (Table 3).
Grazing also reduced the quantity of S. amygdaloides (peachleaf willow,
6% - 1% cover, p = 0.083 s.v./0.188 p.v. ) and Cornus stolonifera (red osier
dogwood, 1.6 - 1.0% cover, p = 0.063 s.v./0.198 p.v) (Table 23). These species
were grazed wherever they co-occurred with willows.
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The loss of willows may increase erosion and increase beaver harvest of
mature cottonwood. First, S exigua colonization of sandbars stabilizes
streambanks. So, if willows are degraded, streambanks erode rapidly (Hansen
1988). And second, because beaver prefer willow and cottonwood saplings to
mature cottonwoods, willow presence diverts them from harvest of mature trees
(McGinley and Witham 1985). On several ranches where all that remained of
the riparian vegetation were large cottonwoods and herbaceous plants, the trees
were being felled by beaver. This causes loss of shade for cattle, and of tree
roots to stabilize banks.
Grazing did not affect total forb cover (17% ungrazed and 21% grazed),
but did affect graminoid cover (Table 23, and Tables 17 vs. 26). Grazing
significantly reduced only one grass: the non-native Phalaris arundinacea (reed
canary grass) declined from 20% to 0.3% cover with grazing (p = 0.0004
s.v./0.009 p.v.)(Table 23). The presence of Phalaris in this vegetation type may
affect willow use by cattle, either as an attractant or a diversion. Loss of Phalaris
may favor the two native associates which increased with grazing: Eleocharis
palustris (spike rush, 0.01% to 0.1% average cover, p = 0.079 p.v./0.239 s.v.)
and Hordeum jubatum (foxtail barley 0.01% to 0.1% cover, p = 0.036 p.v./0.161
s.v.).
Agrostis stolonifera also increased with grazing (2% to 4%), but the
change was not significant.
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Richness & Exotics. There were no significant differences between
ungrazed and grazed Salix exigua thickets in either richness/site (22.0 vs. 23.1
spp), or in richness in any life form/site category. The percent of species/site
which were exotic was also comparable: 46% + 13% for ungrazed, and 41% +
9% for grazed. Grazed sites showed substantial loss of non-native cover (from
39% to 20%), primarily resulting from the loss of Phalaris.
Environment. Soil textures of grazed and ungrazed stands differed
significantly. Grazed sites averaged 67% sand and 23% silt, while ungrazed sites
had less sand (53%, p = 0.021 s.v./0.035 p.v.) and more silt (35%, p = 0.008
s.v./0.016 p.v.) (Tables 27 & 8). This is unlikely to be attributable to difference in
river location, since the average location of ungrazed sites (river mile 162 + 147)
isn’t that different from grazed sites (mile 97 + 107). It seems more likely that the
taller, denser willows on ungrazed sites slow river flows sufficiently to capture
more transported silts or to prevent export of silts. Conversely, heavily grazed
willow stands commonly had more bare ground susceptible to wind and water
erosion. Ungrazed and grazed S. exigua sites were insignificantly different from
one another with respect to other environmental variables tested (Table 27).
Populus angustifolia Communities
Eight ungrazed and thirteen grazed P. angustifolia stands were sampled.
All were between miles 0 and 100 of the study region, i.e. between Emigrant and
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Reed Point, MT. Cow pats were absent from the ungrazed sites, and averaged
3.5% cover on the grazed sites.
Dominance. Grazed Populus angustifolia stands (148% +23%) had
significantly less cover than ungrazed stands (168% + 26%) (p = 0.098 s.v./0.082
p.v.) (Table 24, and Tables 17 & 26). The cottonwood canopy, out of reach of
grazers, was apparently unaffected.
Native shrubs are greatly reduced by grazing (Table 24). Native shrub
cover declined from 46.7% to 7.8% average cover (p = 0.005 s.v./p = 0.0001
p.v.). The nine most prevalent native shrubs all declined with grazing, four of
them significantly. Cornus stolonifera (red osier dogwood) virtually disappeared,
decreasing from 10.2% to 0.0% cover (p = 0.058 s.v./0.008 p.v.).
Symphoricarpos occidentalis declined dramatically, from 15.1% to 2.5% cover (p
= 0.200 s.v./0.086 p.v.). Rosa sayi/R. woodsii (4.9% to 0.9% cover, p = 0.173
s.v./0.074 p.v.) and Ribes setosum (redshoot gooseberry) (0.5% to 0.0%, p =
0.143 s.v./0.046 p.v.) also declined. Five other shrubs which provided
(insignificantly) less cover in grazed than ungrazed stands were Juniperus
scopulorum (Rocky Mountain juniper), Rhus trilobata (skunkbush sumac),
Shepherdia argentea (buffaloberry), Salix amygdaloides and Ribes aureum
(golden currant).
Cornus stolonifera (sites GMX and GJX) and Salix amygdaloides (sites
GKX, G2B2) were seen browsed in other vegetation types; Ribes sp. and to a
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lesser extent Symphoricarpos are known to be browsed by cattle (Kauffman et.
al. 1983b). Rosa sp. appeared to decline from trampling, rather than from
browsing, because it persisted immediately adjacent to large trees and between
fallen logs – places where it was protected from trampling, but could have been
browsed. No other shrubs showed this pattern.
While grazing did not reduce overall forb cover, three individual species
showed significant declines (Table 24). The native Smilacina stellata (starry
false Solomon’s seal) dropped from 2.3% to 0.3% average cover (p = 0.279
s.v./0.007 p.v.), and from 100% to 23% constancy. Solidago gigantea (late
goldenrod) declined from 1.2% to 0.0% average cover (p = 0.084 s.v./0.017 p.v.)
and from 75% to 8% constancy. The exotic weed Cirsium arvense (Canadian
thistle), prevalent in willow thickets, also lost cover with grazing (4.0% to 0.4%
cover, p = 0.025 s.v./p = 0.003 p.v.).
The cover of non-native forbs as a group seemed to increase with grazing,
from 6% to 10% average cover, though insignificantly (Table 24). Centaurea
maculosa (knapweed), absent from ungrazed sites, averaged 0.6% cover and
38% constancy on grazed sites. Cynoglossum officinale (houndstongue)
increased from 0.0% to 1.4% average cover, and from 13% to 62% constancy
with grazing. The native Glycyrrhiza lepidota (wild licorice), which many ranchers
considered a problem weed, doubled its average cover with grazing (2.2% to
4.8%).
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Grass cover increased significantly with grazing, from 20% to 39% on
average (p = 0.010 s.v./0.029 p.v.) (Table 24), perhaps due to reduction of shrub
competition. The cover increase was mostly due to the near doubling of nonnative grasses (16% to 32% cover, p = 0.071 s.v./0.115 p.v.). Exotic Elymus
repens (quackgrass) increased from 1% to 14% cover (p = 0.044 s.v./0.094 p.v.).
Other grasses which increased with grazing, albeit not significantly, were the
exotics Poa pratensis, Bromus inermis and Dactylis glomerata, and native
Agrostis stolonifera. Phalaris arundinacea, which disappeared from willow
thickets with grazing, was likewise consumed in P angustifolia stands; it
averaged 5.3% cover in ungrazed locations, but zero cover in grazed sites (p =
0.109 s.v./0.028 p.v.).
Richness. The species richness of the narrowleaf cottonwood community
declines with grazing, from 19.8 to 16.0 species per site, due to a significant loss
of native forbs (Tables 17 & 26). Tree diversity was unchanged. Native shrub
diversity was reduced insignificantly, from 5.3 to 3.5 species/site (p = 0.153
s.v./0.111 p.v.). Native forb richness dropped significantly, from 5.0 to 2.3
species/site (p = 0.013 s.v./0.004 p.v.). Native grass richness declined slightly,
from 1.5 to 1.0 species/site. Overall native species richness declined from 12.9
to 7.9 species/site (p = 0.005 s.v./0.003 p.v.). Non-native species richness
increased insignificantly (6.9 to 8.1 spp, p = 0.379 s.v./0.382 p.v.).
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Exotics. Grazing increased the dominance of exotic plants. The percent
of total cover comprised of non-native species increased significantly with
grazing, from 14% + 10% to 27% + 14% (p = 0.026 s.v./0.039 p.v.). Considering
the ground layer only, the cover of non-native forbs and grasses increased from
23% + 17% to 42% + 25% cover (p = 0.054 s.v./p = 0.076 p.v.) (Table 24, and
Tables 17 & 26).
Vegetation Overview. The change in P. angustifolia stands with grazing is
visually striking: while the overstory is unchanged, the exclusively native shrub
cover declines from 47% to less than 8%, and weedy grasses and forbs
(primarily exotic) increase to fill the gaps. Less visually obvious is the loss of
native species richness, including the shrubs Cornus stolonifera, Ribes setosum,
Ribes aureum and Rosa spp, and forbs such as Smilacina stellata and Solidago
gigantea. What are the ecological consequences of this shift in plant community
composition?
Environment. The environments and soil properties of ungrazed P.
angustifolia stands differed from those of grazed sites in two ways, both resulting
from grazing effects on soil capture during the flood stage and/or on rates of
erosion.
Depth to gravel was greater in ungrazed (111 cm + 48 cm) than in grazed
(74 cm + 38 cm) stands (p = 0.084 s.v./0.077p.v.) (Table 27). This may be due
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to higher deposition in ungrazed stands, higher export (erosion) from grazed
stands, or geomorphologic changes downriver. With regard to geomorphic
changes, depth to gravel (Figure 20) and soil surface height (above river water,
Figure 19) both increase substantially with distance downriver in the foothills/P
angustifolia zone (mile 0 to mile 100). Both phenomena are presumably due to
greater deposition of fine sediments with distance downriver. The fact that the
ungrazed stands were slightly offset downriver (average: mile 48) relative to
grazed stands (average: mile 31) (p = 0.36 s.v./0.34 p.v.) raises the third
possibility.
The second difference was that silt content of soils at ungrazed sites
(49%) was higher than silt content at grazed sites (32%) (p = 0.112 s.v./0.075
p.v.) (Table 27). Sand contents were complementary, with ungrazed site soils
(36% sand) less than those at grazed sites (56%) (p = 0.18 s.v./p = 0.13 p.v.).
Again, the ungrazed sites may capture more silt, the grazed sites may lose more
silt, or the process may be geomorphic (independent of vegetation/ grazing).
Because grazed P angustifolia sites are sandier and less silty than their
ungrazed counterparts at the same river mile (miles 0 – 100, figures 25 & 26), we
reject the geomorphic hypothesis.
As we hypothesized for willow thickets, we suggest that the soil texture
difference is due to greater erosion at grazed sites carrying off more silt than
sand. The decrease in total plant cover, the shift from predominantly native
shrub cover to predominantly non-native herbaceous cover, and the exposure of
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bare ground at heavily grazed locations could all be factors. It’s also possible
that ungrazed sites trap more silt from surface runoff, and from the occasional
floods high enough to reach these cottonwood forests (2.4 m above river level).
Populus deltoides Communities
Seventeen grazed and 17 ungrazed Plains cottonwood stands were
sampled between Reed Point and Sidney, MT, a stretch of 400 river miles. Cow
pat cover was absent from the ungrazed sites, and averaged 0.8% cover on the
grazed sites.
Dominance. The impacts of grazing on P deltoides stands are more
subtle, and not as visually striking, as in P angustifolia forests. As the percent
cover cow pats in P deltoides (0.8%) was significantly less than that in P
angustifolia (3.5%, p = 0.03 s.v./0.02 p.v.), it’s possible that Plains cottonwood
forests in this study were not as heavily grazed as the narrowleaf cottonwood
stands. Tree cover, established long ago, is unaffected, because cows can’t
reach it (Tables 24 & 25).
Across all ages of stands, shrub cover declined insignificantly from 41.2%
to 27.2% (p = 0.231 s.v./0.230 p.v.) (Table 25). The decrease in native shrub
cover is greatest in mature stands, as younger stands have little developed shrub
covers (Table 28). If only those stands with average DBH of 50 cm or more are
considered, native shrub cover declined from 37.4% to 24.4% (p = 0.182
100
s.v./0.164 p.v.). Native shrub cover in mature, ungrazed P deltoides stands
(37.8%) on the lower Yellowstone (Boggs 1984) was almost identical to our
measurement. If his six sites are added to our sample the loss of native shrub
cover at grazed, mature sites is significant (p = 0.095 s.v./0.091 p.v.).
One native shrub, Toxicodendron rydbergii (poison ivy) declined
significantly with grazing in our sites, from 8% to 1% on average (p = 0.108 s.v./p
= 0.101 p.v.). Juniperus scopulorum, Vitis riparia, Cornus stolonifera, Salix
amygdaloides, Ribes aureum and other natives decreased, although not
significantly. A few natives, such as Rosa sp., Symphoricarpos occidentalis and
Artemisia cana, increased insignificantly with grazing.
The non-native Russian olive (Elaeagnus angustifolia), the dominant
shrub under cottonwoods with both the highest cover (15% ungrazed/9% grazed)
and the highest constancy (76% ungrazed/65% grazed), was insignificantly
reduced on grazed sites (p = 0.365 s.v./0.365 p.v.) (Table 25). Russian olive’s
dominance of the shrub understory is striking for two reasons. First, it did not
have > 1% cover in any of the cottonwood (or thicket) transects completed in the
1980-1981 survey of the lower Yellowstone (Boggs 1984). Second, a review of
ungrazed P deltoides sites ordered by tree size (DBH) and therefore age of stand
establishment, shows that Russian olive is establishing earlier in succession than
any of the other shrubs of comparable size (Table 28). (P deltoides diameter at
breast height [DBH] has been shown to be closely correlated with age, for the
lower Yellowstone (Boggs 1984)).
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Grazing is expected to increase Russian olive cover, both because cattle
do not remove Russian olive and because their removal of other shrubs reduces
competition with Russian olive. The statistically insignificant reduction observed
on grazed land likely results from management of ranch vs fishing access land.
Ranchers remove the shrub, while fishing access managers cannot address it,
because it is not on the noxious weed list. We hypothesize that seedling
establishment increases with grazing, at least in mature stands, due to reduction
of native shrub cover.
Overall forb cover increased significantly on grazed sites, from 4.6% to
11.4% (p = 0.07 s.v./0.07 p.v.) (Table 25). This gain was primarily in non-native
forbs (2.2% to 8.3% cover, p = 0.04 s.v./0.03 p.v.). Forbs increasing the most
were Taraxacum officinale, from 0.1% to 1.9%, Euphorbia esula from 0.4% to
1.8%, Cirsium arvense from 0.3 to 1.2%, and Medicago lupulina from 0.04% to
0.5%. The increase was significant for Taraxacum (p = 0.11 s.v./0.10 p.v.) and
Medicago (p = 0.09 s.v./0.08 p.v.). Overall, the forb pool shifted from natives
comprising 68% of its cover, to non-natives dominating at 70% of forb cover.
Five of the seven native forbs with the greatest cover on ungrazed sites,
virtually disappeared (to < 0.05% cover) with grazing (Table 25). These included
Solidago mollis, Apocynum sibiricum, Asclepias speciosa and the two forbs
which declined significantly with grazing in P angustifolia stands: Smilacina
stellata and Solidago gigantea. One native forb, Ambrosia psilostachya,
significantly increased with grazing, from 0.2% to 1.1% cover (p = 0.09 s.v./p =
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0.08 p.v.). Native Glycyrrhiza lepidota also increased insignificantly, from 0.2%
to 1.2% (p = 0.19 s.v./0.18 p.v.). Detection of grazing induced changes in
quantities of inconstant species is a common problem (Popolizio et al 1994).
The significant increase in grass cover (from 20% to 39%) associated with
shrub disappearance observed in foothills P angustifolia forests was not
repeated. Ungrazed P deltoides stands already had 29% grass cover, which
increased only slightly to 34% cover on grazed sites (Table 25). Grass cover in
both P angustifolia and in P deltoides stands, ungrazed and grazed, was 80% or
more exotic. The dominant grass in Plains cottonwood stands, non-native
Bromus inermis, was unaffected by grazing (15% down to 13%); the non-native
Poa pratensis doubled its cover (4.3% to 8.7%, p = 0.14 s.v./p.v.); neither
difference was significance.
Richness. Richness of grazed and ungrazed stands was comparable,
with ungrazed locations having 19 + 6.6 species/site, and grazed locations 17.9 +
6.9 species/site. The difference was in shrub diversity: 5.8 ungrazed, 4.2 grazed
(insignificant, p = 0.17) (Tables 17 & 26).
Exotics. The percent of non-native species/site was higher on grazed
(50% + 10%) than on ungrazed sites (43% + 11%), but the difference was not
significant. By life form, native shrubs declined with grazing, at least in the more
mature forests, and non-native forbs increased significantly with grazing. The
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most important exotics in terms of cover, for all sites, were Russian olive, Bromus
inermis, Poa pratensis, and a handful of invasive forbs, in order of declining
dominance (Tables 17 & 26).
In sum, the dominant shrub is exotic and grazing appears to reduce its
competition from native shrubs; exotic forbs increase from 32% to 70% of total
forb cover with grazing, and exotic grasses are maintained at > 80% of total
graminoid cover with grazing.
Environment. None of the environmental variables appeared to differ
significantly between ungrazed and grazed sites (Table 27).
Summary of Grazing Effects
We hypothesized (GrHy 1) that species richness/site would be unaffected
by grazing, and this is supported by our results. Species richness/site was not
significantly changed in gravel (18 + 12 to 24 + 12), sand (25 + 8 to 20 + 14),
willow (22 + 7 to 23 + 6), P. angustifolia (20 + 6 to 16 + 5), or P deltoides (19 + 7
to 18 + 7). (Tables 17 & 26).
We hypothesized (GrHy2) that overall cover would decrease in all
vegetation types with grazing. Although cover did decrease in all types, this was
only significant in S. exigua (111% to 89%)(p = 0.06 sv/0.04 pv) and in P.
angustifolia (168% to 148%)(p = 0.098 sv/0.082 pv) vegetation types, and nearly
significant for sandbars (39% to 19%)(p = 0.105 sv/0.167 pv).
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Grazing effects on canopy (cottonwood) cover varies with stand age.
Populus seedling cover was hypothesized to decline with grazing. Seedlings
were consistently grazed on gravel, sand, and in willow thickets, wherever there
was sign of cattle presence. However cover of seedlings on most sites – both
ungrazed and grazed – was so low that there were no significant changes in
cover with grazing. Grazing has no effect on older canopies, because they are
above browsing height. Future tree canopy will be affected if grazing of
seedlings reduces their survival rate.
Grazing significantly reduced native shrubs on bars, in willow thickets, in
P. angustifolia forest and in mature P. deltoides forest. Physiognomy was most
affected in willow thickets, where both cover and height of Salix exigua was
reduced. There was less reduction in the shrub layer of P. deltoides stands,
because ungrazed forests had less cover of palatable native shrubs to begin with
(26% vs. 47% in P angustifolia), and the non-native Russian olive (15% cover)
wasn’t being browsed. As shrub cover increases with forest age, the impact on
native shrubs was greater in older P deltoides stands.
Total forb cover was not affected by grazing in any community, as
hypothesized, except in Populus deltoides forests where it increased significantly
with grazing (p = 0.07 s.v.).
Graminoid cover was hypothesized to decrease with grazing, but we found
no uniform response across vegetation types. Grass cover was essentially
unchanged on gravelbars (3.0 to 3.5%) and declined insignificantly on sandbars
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(12 to 6%). It also declined in willows (31 to 23%). Grass cover increased
significantly in P. angustifolia stands (20 to 39%, p= 0.01 s.v.), and insignificantly
in P. deltoides (29 to 34%).
Exotic presence might increase due to disturbance, seed introduction and
reduction of competition from palatable natives. It might be especially strong if
they were grazing (chemical or thorny) or trample resistant plants. The percent
of site richness comprised of non-native species varied from 34% to 50% across
all vegetation types (Tables 17 & 26), with no apparent significant changes from
ungrazed to grazed for any one plant community.
We hypothesized that grazing would decrease cover of natives (shrubs,
forbs and graminoids) and increase cover of non-natives (forbs and graminoids)
in every vegetation type (GrHy3). This was true, with a few exceptions (Tables
21-25). On gravelbars, three non-native and one native forb increased
significantly while on sandbars, the native shrub S. exigua declined significantly
with grazing (9.0 to 0.3%). In willows the cover of four native shrubs and one
exotic grass was reduced significantly by grazing, while the cover of two native
grasses increased very slightly, but significantly (0% to 0.1% cover). Altogether,
a total of eight native shrub species occurring in willow thickets and/or
cottonwood stands declined significantly with grazing. In P angustifolia forests,
while two native forbs were reduced by grazing, the non-native grass cover
doubled significantly from 16% to 32% (p = 0.07 s.v.). In P. deltoides stands,
non-native forbs also increased significantly, from 2% to 8% cover (p = 0.03 p.v.).
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Among grasses, two exotics increased in willow. One exotic increased
substantially in P deltoides, and four exotics increased in P angustifolia forests.
One exotic grass, Phalaris, decreased with grazing in all zones and significantly
so in willow thickets (Tables 23-25).
We expected no significant effects of grazing on environmental variables
for any vegetation type. Surprisingly, comparison of bar, willow, and cottonwood
communities suggested several possible impacts (Table 27). On sandbars clay
increased (7% to 11%, p = 0.07 s.v./0.17 p.v.) and organic matter increased
(0.38% to 0.62%, p = 0.05 s.v./0.10 p.v.) with grazing. Despite significant
relationships, we doubt that grazing either caused or was affected by these soil
qualities. On the other hand silt contents of soils were significantly higher in
ungrazed than grazed vegetation in willow (35% vs 23%) and in P angustifolia
(49% vs 32%) communities. Ungrazed stands may have had less bare ground
than grazed, thus capturing more silt from surface flow. And reciprocally, grazed
sites with less vegetation may have had more silt loss due to faster water flows
and more wind erosion.
Comparison of Environmental Factors
Abiotic factors, including surface and subsurface water, climate change
along the rivers, and rich soils are known to contribute to riparian species
diversity (Green and Kauffman 1985; Kauffman et. al. 1985; Fleischner 1994;
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Ohmart 1996). Variability in these factors both laterally (from bar to willow to
cottonwood) and longitudinally along the river (foothills to prairie) is worth
examining. We hypothesized that height above water, depth to gravel, percent
organic carbon and percent nitrogen would increase laterally.
Height Above Water
Access to surface and subsurface water is indexed by the height of the
soil surface above the river ("height above water"). Gravelbars and sandbars are
similarly raised above the river surface, both site types averaged 1.4 meters
height above water. In this study, we found that height above water increases
from gravelbar to upriver willow sites (at 1.8 m) (p = 0.01) and from these willow
to narrowleaf cottonwood stands (at 2.4 m) (p = 0.004). Similarly, height above
water increases in the plains from sandbar (1.4 m) to downriver willow sites (2.3
m) to Plains cottonwood stands (4.4 m).
In addition, height above water increases longitudinally along the river for
willow and for cottonwood. Ungrazed willow transects in the foothills (P.
angustifolia) zone averaged 1.8 m above water; willows in the plains zone
averaged 2.3 m above water. There is an even greater spread for cottonwood:
ungrazed Populus angustifolia sites averaged 2.4 m above water, while P.
deltoides stands averaged 4.4 m above water (Table 8 and figure 19). These
longitudinal differences were significant at p = 0.025, and p = 0.004 when all the
willow and cottonwood sites in this study were included.
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This change in "height above water" can be readily observed as a
substantial increase in bank height as one travels downriver from Emigrant to
Sidney. In some upriver locations in Paradise Valley (Emigrant to Livingston),
narrowleaf cottonwood stands are barely raised above the river edge gravel and
flood readily (personal communication, local rancher); downriver towards Sidney,
there are Plains cottonwood stands growing right up to the edge of eroded sandy
banks, which drop off more than seven meters to the river below.
Depth to Gravel
Subsurface water may move readily through gravel layers below the soil
surface, and so depth to gravel is another measure of potential water availability
for plants (figure 20).
We hypothesized that depth to gravel would increase laterally. In the
foothills zone, depth to gravel increases significantly from sandbar sites (28 cm
average) to Salix exigua thickets (116 cm) (p = 0.0002), but foothills zone S.
exigua and P. angustifolia stands had roughly equivalent depths to gravel (116
cm and 111 cm, respectively) (Table 8).
The equivalent depths to gravel can be explained by the deposition
processes taking place in the foothills. In this zone, the original gravel bed
surfaces are covered by overbank deposits of coarse to medium textured sands.
The sedimentation curve increases steeply for the first fifty years after site
establishment, and then within 100 years levels off (Merigliano and Polzin 2003).
109
Sandbar willow dominates lower elevation old channels that have filled in with
sand, while cottonwoods establish on gravel bar crests. As cottonwood
seedlings grow into saplings, and overbank deposits accumulate on the bar
crests, sandbar willow will also establish with the cottonwoods (c. 25 years). By
the time the cottonwoods have reached pole stage (c. 47 years), the willow
understory is gone (Merigliano and Polzin 2003). However, our soil data indicate
that sandbar willow thickets that established without cottonwoods, on lower
elevation sandy surfaces overlaying old channels, may continue to persist.
The result is that both P angustifolia and S exigua communities can be
found, the first at higher elevations on top of gravel bar crests, the latter at lower
elevations in old channels. There is twice the variation in the depth of the original
gravel deposit, than in the overbank deposit surface height (Merigliano and
Polzin 2003), which explains why depth to gravel is comparable for the two
communities even though cottonwoods are higher above water.
In the plains, depth to gravel increased from sandbars (28 cm) to Salix
exigua thickets (106 cm) (p = 0.00), to P. deltoides stands, with a conservatively
estimated 153 cm average depth (significant at p = 0.00). In some cases depth
to gravel exceeded the reach of our 152 cm auger. Where possible depth to
gravel was estimated from adjacent riverbanks; this was sometimes as much as
four meters. In short, average depth to gravel was 106 - 116 cm for all Salix
exigua and for narrowleaf cottonwood, and readily exceeded 150 cm for Plains
cottonwood. The greater depth to gravel found in the plains corresponds to
110
greater heights above water found there, as the sedimentation curve continues to
climb through time to as much as seven meters above the river at Sidney, MT
(figure 19).
Calcium Carbonate and pH
Soil calcium carbonate and pH both increase significantly with distance
downriver. The soil's calcium carbonate content was negligible in the foothills. It
began to rise (to values > 1 percent equivalency) near Reedpoint, at the
transition from P. angustifolia to P. deltoides. It continued to increase
downstream to values as high as 5.7 (squared multiple r = 0.75; p = 0.000)
(figure 21). CaCO3 concentrations in river water generally increase with distance
downstream (Kelly 2005). The increase in CaCO3 downstream might be due to
either increasing deposition (silts in river water), reduced leaching (with
decreased precipitation), or both.
With the increasing CaCO3, soil surface pH gradually becomes more basic
(figure 22). Foothills sandbar soils had an average pH of 7.7, while their
downriver counterparts were much more basic (8.4 pH, Tables 8 & 27 - ungrazed
and grazed). The same range was found when soils of ungrazed upriver Salix
exigua stands were compared with soils of downriver Salix exigua stands (pH 7.9
vs 8.2), and when soils of ungrazed P. angustifolia stands (pH 7.8) were
compared with P. deltoides soils (pH 8.1, Table 8). An analysis of variance of
soil pH against river mile gave a p value of 0.0000.
111
There is also a slight lateral increase in CaCO3 from sandbar to later seral
communities (Figure 21), perhaps due to the additional deposition of river silts.
In the foothills, the increase is from 0.04 percent equivalency in sandbars, to 0.4
in both S. exigua and P. angustifolia. In the plains, sandbar soils have 3.0
percent equivalency CaCO3, S. exigua 3.2 and P. deltoides 3.4. This could in
turn affect soil pH in the respective plant communities. An analysis of variance of
sandbar, willow, P. angustifolia and P. deltoides soils, with pH as the dependent
variable, was marginally significant (p = 0.10).
The slightly higher pH downriver may help explain the presence of
Russian olive in the plains, and its absence in the foothills zone, as it is believed
to prefer slightly alkaline soils (Olson and Knopf 1986).
Soil Development Measures: Organic Carbon and Nitrogen
Percent organic carbon and percent total nitrogen were measured as
indices of biological input, and were hypothesized to increase laterally (bar to
willow to cottonwoods). Our data support this hypothesis. For the foothills zone,
organic carbon increased from 0.37% for sandbar (all ungrazed sites) to 1.35%
for upriver Salix exigua soils (significant at p = 0.05), and further to 2.80% for P.
angustifolia soils (significantly greater than willow soils at p = 0.0002) (Figure 23,
Table 8). There was a corresponding increase in total nitrogen from 0.023%
(sandbars) to 0.090% (upriver willows) to 0.168% for P. angustifolia (Figure 24,
Table 8).
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In the plains, organic carbon increased from 0.37% in sandbar soils (all
ungrazed sites) to 0.62% in plains S. exigua, and to 1.86% for P. deltoides soils
(Table 8, Figure 23). Total nitrogen also increased, from 0.023% for sandbars
(all ungrazed sites) to 0.039% for plains S. exigua, and to 0.123% for P. deltoides
(Table 8, Figure 24). This pattern was also found by Boggs for the lower
Yellowstone (1984).
A longitudinal comparison finds that foothills willow and cottonwood soils
had higher levels of organic carbon and nitrogen than their downriver
counterparts. The soil organic carbon content fell significantly from P.
angustifolia soils (2.80%) to P. deltoides soils (1.86%) (p = 0.07 s.v./0.04 p.v.).
The decline in soil organic carbon from upriver (1.35%) to downriver (0.62%)
willow sites was not significant (p = 0.12). Total soil nitrogen shared the same
pattern: it was higher for foothills soils than plains soils, in both the willow and the
cottonwood communities (Figures 24 & 23, Table 8), but these differences were
not (quite) significant (p = 0.13 for both).
A variety of factors might contribute to this difference. Greater annual
precipitation (and less evaporation) in the foothills might lead to higher
productivity. Cooler summer temperatures in the foothills might result in slower
decomposition of soil humus. Stand ages might be greater up than downriver, if
there is a longer flood plain turnover period for cobble substrates upriver than
sandy substrates downriver. Foothills Salix exigua that establish without
cottonwood on sandbars overlaying old channels, aren't age limited by being
113
overtopped by the growth of P. angustifolia - as willows in the Plains zone are (or
were) by P. deltoides growth. Additionally, the sedimentation curve for the
foothills zone levels off after 100 years (Merigliano and Polzin 2003), so height
above water does not appear to rise too high for S. exigua to obtain moisture.
(Even P. angustifolia stands – highest above water of the vegetation types in the
foothills - averaged only 2.4 m above the river, while downriver S. exigua are
averaging 2.3 m above water - thus demonstrating the willows' tolerance.)
Perhaps foothills S. exigua thickets on the whole survive longer and are older
than plains willow thickets?
Soil Texture
Variation in soil texture showed both lateral and longitudinal patterns,
which we had not hypothesized. Laterally, sand drops from an average of 72%
for sandbars to 53% for Salix exigua soils (significant at p = 0.009), and declines
further to 36-42% sand in cottonwood soils (p = 0.084 s.v./0.092 p.v.). With the
drop in sand (%) over time, silt (%) and clay (%) both increase reciprocally. The
soils change from sands and sandy loams to loams. Longitudinally, the foothills
soils in both willow and cottonwood communities had less sand (%) and more silt
(%) on average than their plains counterparts - but the differences were not
significant (Figures 25-27; Table 8).
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Electrical Conductivity
The electrical conductivity of the soils from each transect was measured, but
no patterns were found with relation to plant community, lateral position or
longitudinal position (Table 8, Figure 28). Averages for vegetation types ranged
from 0.37 + 0.09 mmhos/cm for sandbars, to 0.57 + 0.44 mmhos/cm for
downriver Salix exigua. High standard deviations for these values were
characteristic.
Vegetation/Environment Relations
Vegetation of the three zones may be determined by differences in age
(through succession) or by differences in the environment (laterally or
longitudinally along the river). The successional and the lateral gradient
correspond, and here the changes in vegetation and environment interact.
The established view (Boggs 1984, Hansen 1988) is that in general the
bar, willow and cottonwood communities replace one another serally, as Salix
and Populus establish together on bars, grow into co-dominants in thickets and
then the willows die and the cottonwoods mature into forests. While this appears
to have been accurate for the plains zone of the Yellowstone 20 years ago, it
does not appear to be happening today due to very poor Populus deltoides
reproduction. In the foothills, Populus angustifolia and S exigua seedlings both
establish on gravel bar crests, where they will grow into co-dominant thickets,
115
and then develop into cottonwood forests (Merigliano and Polzin 2003).
However, willows also establish without cottonwoods on lower lying sandbars in
the foothills (Merigliano and Polzin 2003).
The series might be externally (allogenically) or internally (autogenically)
driven or both. The allogenic hypothesis states that the environment is dried as
flood deposits of sand and silt, trapped by vegetation, increasingly distance the
vegetated surface from the water below. Early seral plants are eliminated by
drought. We have shown (above) that height above water increases in both
foothills and plains as the community ages from bar to willow thicket to
cottonwood forest. Depth to gravel shows the same pattern in the plains. In
mature forests, hydric shrubs (e.g. Salix) are replaced by mesic shrubs (e.g.
Symphoricarpos).
Two time-determined mechanisms might drive an autogenic transition in
species composition. First, if ground layer plants are excluded by shade, the
exclusion occurs only after taller plants accumulate wood and overtop plants they
eventually dominate. Willows dominate the forbs of bars, and cottonwoods
eventually dominate willows.
Second, while hydric plants (eg Salix, Carex,
Juncus, Cornus, Ribes hudsonianum) may vanish in the drying environment, it
takes time to accumulate seed for succeeding xeric plants. While cottonwood
and willow seeds are delivered to bars in or on the water or via the wind, riparian
hydric and mesic shrubs more likely arrive by a biotic mechanism. Specifically,
the fact that almost all riparian mesic shrubs have berries (Juniperus, Rhus,
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Shepherdia, Symphoricarpos, Elaeagnus, Toxicodendron, Vitis, Rosa) suggests
that seed delivery by birds increases in the maturing (aging) cottonwood
community when the trees are large enough to provide nesting sites. Wide
ranging mammals probably also deliver borages and burs adapted either to
hydric streamside sites (e.g. Xanthium) or to dry forest (e.g. Arctium, Glycyrrhiza,
Cynoglossum). Similarly, small mammals may cache and thereby distribute
Russian olive berries (Currier 1982 in Olson and Knopf 1986). This is the
autogenic hypothesis. Both allo- and autogenic processes apparently act in
concert.
Plains Cottonwood Reproduction on the Yellowstone
Populus deltoides reproduction may be threatened, as seedlings and
saplings are nearly absent from ungrazed sandbars and willow thickets in the
plains, compared to the 21% cover on bars and 30% cover in thickets found 20
years ago (Boggs 1984). Although we found that cattle grazed cottonwood
seedlings wherever they had access to them, it is critical to note that
cottonwoods are not reproducing well even when protected from grazing. The
existing literature, our data and rancher observations suggest several potential
contributing factors that deserve further research attention.
117
Climate Change?
A study on long term Populus angustifolia reproduction along the upper
Yellowstone (Gardiner to Springdale) found that there was a high level of flood
plain creation from 100 – 150 years ago, and concurrently, a surge in cottonwood
establishment (Merigliano and Polzin 2003). Cottonwoods did less well in the
past century, and still less well in the past fifty years as the river system became
less dynamic. The proportion of young cottonwood trees declined from 1948 to
1976, and dropped further to 1999 (Merigliano and Polzin 2003). Although
cottonwood seedlings did establish on new deposits created by the 1996-1997
floods, flood plain creation in those two years was not as extensive as it had
been in previous floods of comparable magnitude. On deposits older than 199697, seedlings are rare to absent (Merigliano and Polzin 2003).
They hypothesize that in addition to bank stabilization (which appears to
have been a minor factor upriver of Livingston until very recently), there have
been alterations in stream flow and sediment load, driven by climate change.
The near absence of low terraces of modern origin along the upper Yellowstone
River supports this (Merigliano and Polzin 2003). The Little Ice Age, which
occurred in North America (and Europe) from the 1400s to the mid to late 1800s,
was associated with more frequent large floods and greater sedimentation rates,
resulting in more fluvial activity (Merigliano and Polzin 2003, citing eight different
sources). They hypothesize that the warming of the climate since, with a
118
concomitant drop in river activity, could account for reduced flood plain and
cottonwood establishment along the upper Yellowstone over the past century.
It would be worth replicating their study – of cottonwood age distribution
and floodplain age, extent and distribution – on the lower Yellowstone, to see
whether the same patterns hold true. It would be a further test of their
hypothesis, and could shed some light on the status of P deltoides reproduction.
Hydrologic Change
Although the Yellowstone itself is not controlled, its major tributaries the
Big Horn, Tongue and Powder River are dammed. These rivers all join the
Yellowstone below Billings. In addition, there are irrigation outtakes from the
Yellowstone itself (Marlow 2005). The historical records of spring flood levels for
the Yellowstone should be examined, to determine if the flooding pattern has
changed significantly in the past twenty years, as this could affect P. deltoides
establishment.
Sediment Pollution
In addition to longer term climate change, another more recent factor may
be at work. Sediment loads in the river increased following the 1988 Yellowstone
fires (Ewing 1996), with 42 – 156% increases in sediment load at Corwin
Springs, upriver of Emigrant (Merigliano and Polzin 2003). Perhaps this
119
additional sediment accounts for the healthy P angustifolia establishment with the
1996-1997 floods, in contrast to near lack of establishment during prior floods?
Higher sediment loads since the fires are having negative effects on the
lower Yellowstone, according to at least four ranchers who participated in this
study. They report that since the fire, more bars are forming in the river, which in
turn become nurseries for weeds. Without any weed control on these mid river
islands, they become continual suppliers of weed seeds to riverbank riparian
pastures. Second, flooding on their pastures now deposits much coarser
sediments than in the past – so coarse that the pastures are ruined and will grow
nothing but a sparse cover of weeds. A couple ranchers have addressed this by
plowing off the coarse deposits and replanting. One has resorted to building
berms between the river and his riparian pastures to prevent future flooding. A
fourth had to abandon the ruined pasture.
We hypothesize that this increase in coarse sediment could be
contributing to either or both of the changes seen along the lower Yellowstone
since the early 1980s: a dramatic increase in the percent cover of non-native
(often weedy) species, and a decline in Plains cottonwood reproduction.
Possibly the coarseness of recent deposits is detrimental to the establishment of
P deltoides, but favors non-native weeds?
How could the river be carrying coarser sediment further downriver than it
used to do? Perhaps flood flow rates have increased due to either streambank
stabilization projects and/or a reduction in the riparian vegetation cover that
120
slows floodwaters. There could be a self-sustaining feedback loop: if coarser
deposits mean less vegetation cover, leading to greater erosion, this would
perpetuate the higher sediment pollution levels.
We are reminded that the biotic (e.g. vegetation) and abiotic (e.g. river
flow rates, sediment pollution, deposition processes) aspects of riparian
ecosystems continually interact and affect the other. Although cyclic change is
an inherent characteristic of these ecosystems, directional change is another
matter. Defined as “a general shift in the environment due to a widespread
change in a driver such as flood frequency or sediment supply” (Merigliano and
Polzin 2003), directional change could destabilize the Yellowstone’s riparian
ecosystems.
Recreation
Heavy recreational use may impact cottonwood reproduction, as well as
riverside vegetation in general. In the upstream P angustifolia zone, cover of
cottonwood seedlings was much higher on four little recreated ungrazed sites
(8.8% cover, sites UCA, UDA, UEA and UIA, Table 5) than on two heavily
recreated ungrazed sites (0.2% cover, sites UJA/UJA2, UMA/UMA2, Table 5) (p
= 0.06 s.v./p.v.). At the sites with healthy cottonwood establishment, forbs
provided 0.4% cover, almost exclusively native grasses contributed just 0.5%
cover, and only 4.4% of the total cover was comprised of non-natives. At the
heavily recreated sites, grasses dominated with 8% cover (4% native, 4% exotic),
121
forbs added another 3% cover, and 51.6% of total cover consisted of non-natives
(p = 0.07 s.v./0.02 p.v., for percent non-native cover). Possibly recreation is
impacting not just cottonwood seedlings, but the gravelbar plant community as a
whole.
While there could be unidentified factors making some gravelbars suitable
for seedlings, and others not, the impacts of recreation on narrowleaf cottonwood
seedling establishment deserves further investigation.
122
CONCLUSIONS 1
Ungrazed Riparian Vegetation
Species richness/site (VgHy 1) varied among vegetation types, generally
falling with distance from the river’s edge. The coarse substrate of gravelbars,
however, supported the lowest richness/site of any type. The differences in
richness were not significant, except that the most diverse vegetation type
(sandbars) was marginally significantly richer than the least diverse, gravelbars
(p = 0.10 s.v.).
Non-native richness (VgHy 2) was highest for sandbars and gravelbars
when averaged across all plots of each vegetation type, or when measured as
percent of richness in all sites of that vegetation type. Non-native richness
calculated per individual site was highest for sandbars. Non-native richness
increased longitudinally downstream in willows and cottonwoods, but not
significantly.
While the percent low constancy species (VgHy 3) fell from shore to
cottonwood it was highest in Salix exigua thickets.
The high richness was due
primarily to higher levels of native forbs. Non-natives on average are more
______________
1
Conclusions follow the hypotheses posed in the introduction. Parenthetic
numbers correlate them.
123
constant (VgHy 4) in a vegetation type and range across a wider variety of
communities than natives do.
The cottonwood canopy (VgHy 5) is short-term stable, but its future
depends on its reproduction. Upriver, P angustifolia's seedlings are numerous on
ungrazed gravelbars without heavy recreational use. Downriver, Populus
deltoides is reproducing poorly on sandbars, and its minimal presence in willow
thickets suggests that it has not established well for eight - ten years.
Shrubs are important in all stages. On bars Salix exigua established
successfully, especially on sandbars, and it grows into thickets on ungrazed
locations. Downriver Tamarix chinensis, is present with low cover but high
constancy on both sand and gravelbars; thus, it may expand as it has in the
southwest. Inland hydric and mesic native shrubs are thriving in ungrazed P.
angustifolia and P. deltoides forests. Plains forests species composition is
challanged by a vigorously increasing exotic shrub, Elaeagnus angustifolia
(Russian olive).
In the herbaceous layer, non-native dominance increases inward from the
river with community age. The herbaceous layer on sandbars and gravelbars is
about equally split between forbs and graminoids, with non-natives providing
almost half of the cover and species richness of each life form. In willows, exotic
grasses and forbs dominate the understory (> 70% of herbaceous cover). In
cottonwoods, different exotic grass species (Elymus repens, Bromus inermis and
Poa pratensis) dominate the herbaceous layer and forbs are secondary. Non-
124
native herbs comprise 76% of herbaceous cover in Populus angustifolia forests
and 79% in P. deltoides stands.
Exotics are strongly invading (VgHy 6) the Yellowstone River’s riparian
communities, both grazed and ungrazed. Over the past 20 years in the plains,
Russian olive has increased from < 1% average cover to 15% average cover.
Tamarisk has increased from non-existent to common on sand and gravelbars.
And non-native richness has doubled across all vegetation types. Meanwhile the
percent of total cover comprised by non-native species has tripled in sandbars,
quadrupled in S. exigua thickets and multiplied nine-fold in P. deltoides forests
(cf. Boggs 1984).
Physical factors determine community siting in space and time (VgHy7).
Decreasing water availability, as indicated by increasing height above water from
shore though willow to cottonwood communities, may eliminate the first two
communities (allogenic succession). Stand age probably contributes to this
change as cottonwoods over-top willows and attract birds introducing berry
seeds (autogenic succession).
Grazed Riparian Vegetation
We hypothesized (GrHy 1) that species richness/site would be unaffected
by grazing, and this is supported by our results. Species richness/site was not
significantly changed in any of the vegetation types studied (Tables 17 & 26).
125
Overall cover (GrHy 2) decreased with grazing in all vegetation types,
especially in P. angustifolia forests, willow thickets and on sandbars.
Cottonwood trees are most impacted as seedlings on bars and in willow thickets.
Native shrubs were reduced by grazing in all vegetation types, with Salix
exigua, Salix amygdaloides, Cornus canadensis, Ribes aureum, Ribes setosum,
and Symphoricarpos most affected. Rosa spp. lost cover with trampling. By
reducing competition for the exotic shrubs (Elaeagnus angustifolia and Tamarix)
grazing may favor them at the expense of native shrubs and trees of the future.
Total forb and total graminoid cover was not significantly affected by
grazing, except in Populus angustifolia stands where grass cover increased
significantly and in Populus deltoides forests, where forbs increased significantly.
In both cases, the increases were due to increases in non-native species cover.
As expected native shrub and graminoid cover declined with grazing,
while non-native forb and grass cover increased with grazing. Total native forb
cover did not change significantly in any vegetation type, as some species
decreased while others increased with grazing.
Grazers did not affect their environments significantly (GrHy3). Soils of
grazed sandbars contained significantly more clay than grazed sandbars. Soils
of grazed willows and P. angustifolia stands contained significantly less silt and
more sand than their ungrazed counterparts.
126
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APPENDICES
142
APPENDIX A
TABLES
TABLE 1. Basin characteristics and annual streamflow statistics at selected sites, Yellowstone River Basin
(Number of years in analyses refers to complete years used in computation of annual streamflow statistics.)
Gauging
Station
number
Streamflow gauging station
6186500 Yellowstone River at Yellowstone Lake
Outlet, YNP
6191500 Yellowstone River at Corwin Springs, MT
Elevation
(m above
sea level)
2356
Annual streamflow
Drainage
Mean
Mean Coefficient Number of
area
annual
annual
years in
of
analyses
(m3/sec) (ft3/sec) variation
(km 2)
2606
37.6
1328
67
0.23
6794
87.9
3104
0.21
90
1385
9197
105
3731
0.19
71
6214500 Yellowstone River at Billings, MT
939
30,549
198
6988
0.23
68
6309000 Yellowstone River at Miles City, MT
711
124,980
324
11,440
0.23
69
6329500 Yellowstone River near Sidney, MT
573
178,980
361
12,750
0.27
84
6192500 Yellowstone River near Livingston, MT
Modified from Zelt 1999
143
1548
All termperatures in degrees Fahrenheit.
"Average annual precipitation" and "Average annual temperature" have been adjusted for departures from "Normal."
The "Normal" is the average value of the meteorological element over a time period, in this case 1961-1990.
M = Insufficient or partial data. M is appended to average and/or total values computed with 1-9 daily values missing.
"--" = No record. Data not recorded, determined unreliable by quality control checks, or not received in time for
publication.
* River miles are approximate river distances from Big Creek, MT, the upriver end of this study.
Based on river miles for the MT Fishing Access Sites; MT Fish, Wildlife & Parks website
Source: National Climatic Data Center, National Oceanic and Atmospheric Administration,
U.S. Department of Commerce (http://www5.ncdc.noaa.gov/pubs/publications.html#CD)
144
Table 2. Montana precipitation and temperature data for the Yellowstone River valley.
River Average Annual Years of Average Yrs of
Jan. '01
July '01 # of frost
Location
Elevation
Mile* Precipitation
Record, Annual Record, Average
Average free days,
Lat
Long
feet
m.
inches
mm
Precip Temp
Temp Min Temp Max Temp 10 yr avg
Livingston 12S 45 29 110 34W 4870 1485
23
16.95
430.5
50
43.6
22
15.7
81.9
102
Livingston AP 45 42 110 27W 4653 1419
36
15.73
399.5
63
45.4
32
-85.2
106
Big Timber
45 50 109 57W 4100 1250
75
-93
-90
18.4
86.0
129
71
45.8
69
13.7
88.9
127
Columbus
45 38 109 16W 3585 1093
121 M 10.82 M 274.83
Billings WP
45 46 108 29W 3097 944
173
13.96
354.6
95
48.8
95
M 19.0
89.9
144
Huntley
45 55 108 15W 3000 915
185
14.17
359.9
89
46.2
88
15.6
89.7
128
55
47.4
54
18.4
88.9
139
Hysham
46 18 107 14W 2660 811
258 M 10.91 M 277.11
Forsyth
46 16 106 41W 2515 767
295
14.08
357.6
27
47.4
27
12.2
90.5
139
Miles City
46 26 105 53W 2628 801
349
13.49
342.6
64
46.3
64
-87.9
141
Terry
46 48 105 18W 2248 685
391
-52
41.6
52
11.1
88.7
127
109
45.0
101.0
M 13.3
88.1
145
Glendive
47 6 104 43W 2076 633
441 M 10.51 M 266.95
Savage
47 27 104 20W 1985 605
478
13.96
354.6
96
44.8
94
M 13.5
86.6
122
Sidney
47 44 104 9W
1920 585
499
15.40
391.2
59.00
44.6
59
15.8
85.3
124
Table 3. List of research sites and their locations, elevation and river mile
Location
E edge of Emigrant
N edge of Emigrant
N edge of Emigrant
N edge of Emigrant
N edge of Emigrant
I mi N of Emigrant
I mi N of Emigrant
I mi N of Emigrant
I mi N of Emigrant
3 mi N of Emigrant, Rt 89
3 mi N of Emigrant, Rt 89
3 mi N of Emigrant, Rt 89
3 mi N of Emigrant, Rt 89
3 mi N of Emigrant, Rt 89
10 mi S of Livingston
near Pine Creek KOA
9 mi. NE of Livingston
9 mi. NE of Livingston
9 mi. NE of Livingston
9 mi. NE of Livingston
1/2 mi. N. of Springdale
1/2 mi. N. of Springdale
Just west of Springdale FAS
10 km SW of Big Timber
10 km SW of Big Timber
10 km SW of Big Timber
10 km SW of Big Timber
10 km SW of Big Timber
10 km SW of Big Timber
2nd letter: from A to Z to 4,
upstream to downstream
Year FAS Elevation River
Site
County
acquired (meters) Mile
Code
Park
1962
1713
6 UBX
Park
6.1 UCN
Park
6.1 UCX
Park
6.1 UCA
Park
6.1 UCN2
Park
6.4 UDA
Park
6.4 UDA2
Park
6.4 UDB
1979
1696
6.4 UDX
Park
Park
8.8 UEN
Park
8.8 UEA
Park
8.8 UEN3
Park
8.8 UEB
Park
1983
1694
8.8 UEN2
Park
22.9 UHX
Park
22 UIA
Park
45.4 UJA
Park
45.4 UJA2
Park
45.4 UJX
Park
1963
1523
45.4 UJN
Park
57.5 UKN
Park
1979
1473
57.5 UKX
Park
57.5 UKX2
Sweetgrass
67 UMX
Sweetgrass
67 UMX2
Sweetgrass
67 UMA
Sweetgrass
67 UMA2
Sweetgrass
67 UMB
Sweetgrass
1966
1434
67 UMN2
3rd letter: A = gravelbar; B = sandbar; X = S exigua
P = P deltoides ; N = P angustifolia
145
Ungrazed Sites/transect number
Emigrant FAS T1
Emigrant FAS area: Island downriver T1
Emigrant FAS area: Island downriver T2
Emigrant FAS area: Island downriver T3
Emigrant FAS area: Island downriver T4
Emigrant West FAS T1
Emigrant West FAS T2
Emigrant West FAS T3
Emigrant West FAS T4
Grey Owl FAS, T1
Grey Owl FAS, T2
Grey Owl FAS, T3
Grey Owl FAS, T4
Grey Owl FAS, T5
Pine Creek KOA, T1
Pine Creek area: Ranch T2 ungrazed
Sheep Mountain FAS T1
Sheep Mountain FAS T2
Sheep Mountain FAS T3
Sheep Mountain FAS T4
Springdale Bridge FAS T1
Springdale Bridge FAS T2
Springdale FAS area: Ranch T5 ungrazed
Grey Bear FAS, west side, T1
Grey Bear FAS, east side, T2
Grey Bear FAS, east side, T3
Grey Bear FAS, east side, T4
Grey Bear FAS, east side, T5
Grey Bear FAS, west side, T7
Site Code Key. 1st letter: U = ungrazed
G = grazed
Table 3. List of research sites and their locations, elevation and river mile, cont'd.
Location
4.5 mi W of Reed Pt
4.5 mi W of Reed Pt
4.5 mi W of Reed Pt
4.5 mi W of Reed Pt
2 mi E of Reed Pt
2 mi E of Reed Pt
6 mi SE of Park City
SW end of Billings
3 mi N of Worden, CO Rd 19
3 mi N of Worden, CO Rd 19
3 mi N of Worden, CO Rd 19
3 mi N of Worden, CO Rd 19
3 mi N of Worden, CO Rd 19
at the Park itself
at the Park itself
at the Park itself
at the Park itself
8 mi W of Custer
5.5 mi W. of Hysham
~3.5 mi W. of Hysham
3 mi N. of Hysham
3 mi N. of Hysham
3 mi N. of Hysham
3 mi N. of Hysham
3 mi N. of Hysham
10 mi. E. of Forsyth
10 mi. E. of Forsyth
10 mi. E. of Forsyth
10 mi. E. of Forsyth
10 mi. E. of Forsyth
10 mi. E. of Forsyth
Year FAS Elevation River
Site
County
acquired (meters) Mile
Code
Sweetgrass
96.8 UNN
Sweetgrass
96.8 UNN2
Sweetgrass
96.8 UNX
Sweetgrass
1970
1182
96.8 UNX2
Stillwater
103 UOX
Stillwater
103 UOP
Yellowstone
1982
1156
144 UPP
Yellowstone
1999
1115
156.4 UQX
Yellowstone
193.7 URP
Yellowstone
193.7 URP2
Yellowstone
193.7 URX
Yellowstone
193.7 URB
Yellowstone
1989
1020
193.7 URA
Yellowstone
203 USX
Yellowstone
203 USA
Yellowstone
203 USP
Yellowstone
203 USP2
Yellowstone
1980
974
220.4 UTX
Treasure
1986
927
248.4 UUX
Treasure
1969
251.5 UVP
Treasure
258.5 UWP
Treasure
258.5 UWX
Treasure
258.5 UWA
Treasure
258.5 UWB
Treasure
1980
916
258.5 UWP2
Rosebud
308.3 UXX
Rosebud
1977
865
308.3 UXP
Rosebud
308.3 UXA
Rosebud
308.3 UXA2
Rosebud
308.3 UXB
Rosebud
308.3 UXB2
146
Ungrazed Sites/transect number
Bratten FAS, T1 (18 mi E of Big Timber)
Bratten FAS, T2
Bratten FAS, T3
Bratten FAS, T4
Bratten FAS area: Ranch T3 ungrazed
Bratten FAS area: Ranch T4 ungrazed
Buffalo Mirage FAS T1
Duck Creek FAS, T1
Gritty Stone FAS, T1
Gritty Stone FAS, T2
Gritty Stone FAS, T3
Gritty Stone FAS, T4
Gritty Stone FAS, T5
Pompey's Pillar T1
Pompey's Pillar T2
Pompey's Pillar T3
Pompey's Pillar T4
Captain Clark FAS East Island T1
Amelia Is. area, Myers Br/Howrey Is., T2
Amelia Is. area, Isaac Homestead, T1
Amelia Island, Wildlife Mngmt Area, T1
Amelia Island, Wildlife Mngmt Area, T2
Amelia Island, Wildlife Mngmt Area, T3
Amelia Island, Wildlife Mngmt Area, T4
Amelia Island, 2nd Island, T1
Farwest FAS T1
Farwest FAS T2
Farwest FAS area: Moon Island T1
Farwest FAS area: Moon Island T2
Farwest FAS area: Moon Island T3
Farwest FAS area: Moon Island T4
Table 3. List of research sites and their locations, elevation and river mile, cont'd.
Location
15 km NE of Miles City
15 km NE of Miles City
7 mi NE of Kinsey
7 mi NE of Kinsey
1.5 mi NNE of Savage
1.5 mi NNE of Savage
1.5 mi NNE of Savage
1.5 mi NNE of Savage
1 mi E of Crane
1 mi E of Crane
1 mi E of Crane
1 mi E of Crane
5.5 mi NE of Sydney
5.5 mi NE of Sydney
County
Custer
Custer
Custer
Custer
Richland
Richland
Richland
Richland
Richland
Richland
Richland
Richland
Richland
Richland
Year FAS Elevation River
acquired (meters) Mile
361.2
1986
804
361.2
372.2
1989
783
372.2
479.3
479.3
479.3
1975
594
479.3
491.5
491.5
491.5
1981
582
491.5
509.8
1986
575
509.8
Site
Code
UYP
UYX
UZP
UZP2
U1X
U1Z
U1P
U1P2
U2B
U2X
U2P
U2P2
U4Z
U4P
147
Ungrazed Sites/transect number
Kinsey Bridge FAS T1
Kinsey Bridge FAS T2
Bonfield FAS, T1
Bonfield FAS, T2
Elk Island Wildlife Managemt Area, T1
Elk Island Wildlife Managemt Area, T2
Elk Island Wildlife Managemt Area, T3
Elk Island Wildlife Managemt Area, T4
Seven Sisters Wildlife Managemt Area T1
Seven Sisters Wildlife Managemt Area T2
Seven Sisters Wildlife Managemt Area T3
Seven Sisters Wildlife Managemt Area T4
Diamond Willow FAS, T1
Diamond Willow FAS, T2
Table 3. List of research sites and their locations, elevation and river mile, cont'd.
Location
S of Emigrant
S of Emigrant
S edge of Emigrant
S edge of Emigrant
S edge of Emigrant
6 km NE of Grey Owl
6 km NE of Grey Owl
6 km NE of Grey Owl
6 km NE of Grey Owl
6 km NE of Grey Owl
6 km NE of Grey Owl
6 km NE of Grey Owl
next to Pine Creek KOA
next to Pine Creek KOA
near Pine Creek KOA
near Pine Creek KOA
near Pine Creek KOA
across river from Sheep Mtn
across river from Sheep Mtn
across river from Sheep Mtn
Just west of Springdale FAS
Just west of Springdale FAS
Just west of Springdale FAS
Just west of Springdale FAS
Just east of Springdale FAS
Just east of Springdale FAS
Just east of Springdale FAS
6 mi SW of Big Timber
6 mi SW of Big Timber
6 mi SW of Big Timber
6 mi SW of Big Timber
County
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Park
Sweetgrass
Sweetgrass
Sweetgrass
Sweetgrass
Elevation River
(approx) Mile
1713
1694
1427
1427
1523
1473
1473
1434
0
0
5.9
5.9
5.9
12.5
12.5
12.5
12.6
12.6
12.6
12.6
23
23
22
22
22
45.4
45.4
45.4
57.3
57.3
57.3
57.3
57.6
57.6
57.6
67
67
67
67
Site
Code
GAX
GAX2
GBN
GBN2
GBN3
GFY
GFN
GFO
GGX
GGN
GGN2
GGB
GHN
GHN2
GIN
GIN2
GIA
GJO
GJX
GJN
GKX
GKN
GKA
GKB
GLX
GLA
GLA2
GMN
GMO
GMX
GMO
148
Grazed Sites/transect number
Emigrant: Big Creek area ranch, T1
Emigrant: Big Creek area ranch, T2
Emigrant FAS area ranch T1
Emigrant FAS area ranch T2
Emigrant FAS area ranch T3
Grey Owl area ranch upriver Mill Crk Rd T1
Grey Owl area ranch upriver Mill Crk Rd T2
Grey Owl area ranch upriver Mill Crk Rd T3
Grey Owl area ranch downrvr Mill Crk Rd T1
Grey Owl area ranch downrvr Mill Crk Rd T2
Grey Owl area ranch downrvr Mill Crk Rd T3
Grey Owl area ranch downrvr Mill Crk Rd T4
Pine Creek Area ranch, T1
Pine Creek Area ranch, T2
Pine Creek area ranch #2, T1
Pine Creek area ranch #2, T3
Pine Creek area ranch #2, T4
Sheep Mountain FAS area ranch T1
Sheep Mountain FAS area ranch T2
Sheep Mountain FAS area ranch T3
Springdale FAS area ranch T1
Springdale FAS area ranch T2
Springdale FAS area ranch T3
Springdale FAS area ranch T4
Springdale FAS area ranch T1
Springdale FAS area ranch T2
Springdale FAS area ranch T3
Grey Bear FAS, east side, T6
Grey Bear FAS area ranch T1
Grey Bear FAS area ranch T2
Grey Bear FAS area ranch T3
Table 3. List of research sites and their locations, elevation and river mile, cont'd.
Elevation River
Site
Location
County
(approx.) Mile
Code
c. 18 mi. SE of Big Timber
Sweetgrass
94 GNN
c. 18 mi. SE of Big Timber
Sweetgrass
1189
94 GNA
2 mi E of Reed Pt
Stillwater
103 GOO
2 mi E of Reed Pt
Stillwater
1170
103 GOO2
6 mi SE of Park City
Yellowstone
1156
143.9 GPP
6 mi SE of Park City
Yellowstone
1156
144.1 GPP2
c. 3 mi. N. of Worden
Yellowstone
193.7 GRP
c. 3 mi. N. of Worden
Yellowstone
1020
193.7 GRP2
across river from Park
Yellowstone
203 GSX
across river from Park
Yellowstone
203 GSP
8 mi W of Custer
Yellowstone
220.4 GTP
8 mi W of Custer
Yellowstone
220.4 GTX
8 mi W of Custer
Yellowstone
974
220.4 GTP2
5.5 mi W. of Hysham
Treasure
927
248.4 GUP
10 mi. E. of Forsyth
Rosebud
308.3 GXX
10 mi. E. of Forsyth
Rosebud
308.3 GXP
10 mi. E. of Forsyth
Rosebud
865
308.3 GXP2
372.2 GZP
7 mi NE of Kinsey, adjoins FAS Custer
783
372.2 GZP2
7 mi NE of Kinsey, adjoins FAS Custer
c. 2 mi. NE of Savage
Richland
479.3 G1P
c. 2 mi. NE of Savage
Richland
594
479.3 G1P2
across river from 7 Sisters
Richland
491.5 G2P
across river from 7 Sisters
Richland
491.5 G2A
across river from 7 Sisters
Richland
491.5 G2B
across river from 7 Sisters
Richland
491.5 G2B2
across river from 7 Sisters
Richland
582
491.5 G2P2
near 7 Sisters
Richland
582
491.5 G3P
149
Grazed Sites/transect number
Bratten FAS area: ranch c. 6 mi. west, T1
Bratten FAS area: ranch c. 6 mi. west, T2
Bratten FAS area: ranch c. 9 mi. east, T1
Bratten FAS area: ranch c. 9 mi. east, T2
Buffalo Mirage FAS: adjoining ranch T1
Buffalo Mirage FAS area: DNRC T1
Gritty Stone area ranch, T1
Gritty Stone area ranch, T2
Pompey's Pillar area ranch T1
Pompey's Pillar area ranch T2
Captain Clark FAS T1
Captain Clark FAS T2
Captain Clark FAS: ranch lease T1
Amelia Is. area, Myers Br/Howrey Is., T1
Farwest FAS ranch lease T3
Farwest FAS ranch lease T5
Farwest FAS ranch lease T6
Bonfield FAS area: adjoining ranch T1
Bonfield FAS area: adjoining ranch T2
Elk Island area ranch T1
Elk Island area ranch T2
Seven Sisters FAS area ranch T1
Seven Sisters FAS area ranch T2
Seven Sisters FAS area ranch T3
Seven Sisters FAS area ranch T4
Seven Sisters FAS area ranch T5
Seven Sisters FAS area ranch #2, T1
Origin*
USDA FPNW
N
N
X
X
N
N
N
X
X
N
N
N
N
N
N
N
X
X
X
N
N
N
N
N
N
N
N
N
N
N
N
X
0
N
N
0
N
N
N
N
X
X
N
N
N
N
N
This list is for species found in gravelbar, sandbar, Salix exigua, S. amygdaloides, S. bebbiana, Populus angustifolia,
P. acuminata and P. deltoides communities, only.
* "N" is native, "X" is non-native, "0" means no data given, "both" means both native and exotic subspecies/varieties occur.
"USDA" is the U.S. Department of Agriculture's plant database, at http://plants.usda.gov.
"FPNW" is the Flora of the Pacific Northwest (Hitchcock and Cronquist 1973).
UM is University of Montana's Invader database, at http://invader.dbs.umt.edu.
UM
N
N
N
N
N
N
N
X
N
N
N
N
N
N
N
N
X
X
N
N
N
N
N
N
150
Table 4. Vascular plant species of Yellowstone River riparian communities
Family and Scientific name
Common name
source: Vascular Plants of Montana (Dorn 1984)
Alismataceae Sagittaria cuneata Sheldon
Arrowhead
Amaranthaceae Amaranthus albus L.
White Pigweed, Tumbleweed
Amaranthaceae Amaranthus blitoides S. Wats.
Prostrate Pigweed
Amaranthaceae Amaranthus retroflexus L.
Pigweed amaranth; rough pigweed
Anacardiaceae Rhus trilobata Nutt.
Skunkbush Sumac
Anacardiaceae Toxicodendron rydbergii (Small ex Rydb.) Greene
Poison Ivy
Apiaceae Cicuta douglasii (DC.) Coult. & Rose
Douglas' Water-Hemlock
Apiaceae Conium maculatum L.
Poison Hemlock
Apiaceae Heracleum sphondylium L.
Cow Parsnip
Apocynaceae Apocynum sibiricum Jacq.
Hemp Dogbane
Asclepiadaceae Asclepias speciosa Torr.
Showy Milkweed
Asclepiadaceae Asclepias verticillata L.
Milkweed
Asteraceae Achillea millefolium L.
Yarrow
Asteraceae Ambrosia psilostachya DC.
Western Ragweed
Asteraceae Ambrosia trifida L.
Giant Ragweed
Asteraceae Antennaria microphylla Rydb.
Rosy Pussy-toes
Asteraceae Arctium minus Bernh.
Common Burdock
Asteraceae Artemisia absinthium L.
Sageweed; Absinthium
Asteraceae Artemisia biennis Willd.
Biennial Wormweed
Asteraceae Artemisia campestris L.
Prairie Sagewort
Asteraceae Artemisia cana Pursh
Silver Sage
Asteraceae Artemisia dracunculus L.
Tarragon
Asteraceae Artemisia frigida Willd.
Fringed Sage
Asteraceae Artemisia ludoviciana Nutt.
Sweet Sage
Table 4, cont'd.
Asteraceae Aster ascendens Lindl.
Asteraceae Aster hesperius Gray
Asteraceae Aster subspicatus Nees
Asteraceae Centaurea maculosa auct. non Lam.
N
N
N
X
N
X
N
X
N
X
N
N
N
N
N
X
N
N
N
N
N
N
X/X
X
X
X
N
N
N
X
X
X
N
N
N
N
X
N
X
0
X
N
X
N
N
X
N
N
N
N
N
N
X/X
X
X
X
N
N
N
X
X
X
N
N
N
N
X
N
X
N
X
N
X
N
N
N
N
N
X
N
N
N
N
N
N
N/X
X
X
X
N
N
N
X
X
X
N
151
Long-leaved Aster
Western Willow Aster
Douglas' Aster
Spotted Knapweed
Asteraceae Chrysothamnus nauseosus (Palaas ex Pursh) Britt. Rubber Rabbit-brush, Gray Rabbit-brush
Asteraceae Cirsium arvense (L.) Scop.
Canada Thistle
Asteraceae Cirsium undulatum (Nutt.) Spreng
Wavy-Leaf Thistle
Asteraceae Cirsium vulgare (Savi) Ten.
Bull Thistle
Asteraceae Conyza canadensis (L.) Cronq.
Canadian Fleabane
Asteraceae Filago arvensis L.
Fluffweed
Asteraceae Gnaphalium palustre Nutt.
Lowland Cudweed
Asteraceae Grindelia squarrosa (Push) Dunal
Curly cup gumweed
Asteraceae Helianthus annuus L.
Common sunflower
Asteraceae Heterotheca villosa (Pursh) Shinners
Hairy False Goldenaster
Asteraceae Lactuca oblongifolia (L. pulchella) Nutt.
Blue lettuce
Asteraceae Lactuca serriola L.
Prickly Lettuce
Asteraceae Rudbeckia laciniata L.
Tall Coneflower
Asteraceae Solidago gigantea Ait.
Late Goldenrod
Asteraceae Solidago missouriensis Nutt.
Missouri Goldenrod
Asteraceae Solidago mollis Bartl.
Velvety goldenrod
Asteraceae Solidago occidentalis (Nutt.) Torr. & Gray
Western Goldenrod
Asteraceae Solidago spathulata DC.
Dune goldenrod
Asteraceae Sonchus uliginosus (Bieb.)/S. asper (L.) Hill Marsh Sow Thistle
Asteraceae Tanacetum vulgare L.
Common Tansy
Asteraceae Taraxacum officinale G. H. Weber ex Wiggers Common Dandelion
Asteraceae Tragopogon dubius Scop.
Goatsbeard
Asteraceae Xanthium strumarium L.
Common Cocklebur
Betulaceae Alnus incana (L.) Moench
Alder
Betulaceae Betula occidentalis Hook.
River Birch (Water Birch)
Boraginaceae Asperugo procumbens L.
Catchweed
Boraginaceae Cynoglossum officinale L.
European Hound's Tongue
Brassicaceae Alyssum alyssoides (L.) L.
Alyssum
Brassicaceae Arabis holboellii Hornem.
Holboell's Rockcress
Table 4, cont'd.
Brassicaceae Brassica rapa (=B. campestris) L.
Brassicaceae Camelina microcarpa DC.
Brassicaceae Capsella bursa - pastoris (L.) Medik.
Brassicaceae Descurainia sophia(L.) Webb ex Prantl
Brassicaceae Erysimum asperum (Nutt.) DC.
Brassicaceae Erysimum repandum L.
Brassicaceae Lepidium campestre (L.) R. Br.
Brassicaceae Lepidium densiflorum Schrad.
Brassicaceae Lepidium perfoliatum L.
Brassicaceae Rorippa palustris (L.) Besser
Brassicaceae Sisymbrium altisssimum L.
Brassicaceae Sisymbrium loeselii L.
Brassicaceae Thelypodium integrifolium (Nutt.) Endl. ex Walp.
X
X
X
X
N
X
X
N
X
N
X
X
N
X
N
both
N
X
X
X
X
N
X
X
N
X
N
N
X
X
X
N
N
X
X
X
X
N
X
N
X
N
X
N
X
X
N
N
X
N
X
X
N
N
X
N
N
N
N
X
X
X
N
N
X
X
X
X
N
X
X
N
X
N
X
X
N
X
N
N
N
N
X
X
X
N
X
X
N
X
N
N
X
X
X
N
N
152
Brassicaceae Thlaspi arvense L.
Cannabanaceae Humulus lupulus L.
Caprifoliaceae Lonicera sp.
Caprifoliaceae Symphoricarpos occidentalis Hook.
Caryophyllaceae Lychnis alba P. Mill.
Caryophyllaceae Silene noctiflora L.
Caryophyllaceae Stellaria media (L.) Vill.
Chenopodiaceae Atriplex heterosperma Bunge
Chenopodiaceae Atriplex patula L.
Chenopodiaceae Chenopodium album L. var. album
Chenopodiaceae Chenopodium botrys L.
Chenopodiaceae Chenopodium fremontii S. Wats.
Chenopodiaceae Chenopodium glaucum L.
Chenopodiaceae Chenopodium leptophyllum (Moq.)
Chenopodiaceae Chenopodium pratericola Rydb.
Chenopodiaceae Kochia scoparia (L.) Schrad.
Chenopodiaceae Salsola kali L.
Convolvulaceae Convolvulus arvensis L.
Cornaceae Cornus stolonifera Michx.
Cupressaceae Juniperus scopulorum Sarg.
Field Mustard
Hairy False Flax
Shepherd's Purse
Flixweed
Plains Wallflower
Bushy wallflower
Field Pepper Grass
Common Pepper Grass
Clasping Pepper Grass
Marsh Yellow Cress
Tall tumblemustard
Tumble Mustard
Entire leaved thelypodium
Pennycress
European Hopvine
Honeysuckle
Western Snowberry
White Campion
Bladder Flower Plant
Chickweed
Saltbush
Orache
Lamb's Quarter; White goosefoot
Jerusalem-Oak Goosefoot
Fremont's Goosefoot
Oakleaf Goosefoot
Slim-leaf Goosefoot
Slender-leaved Goosefoot
Kochia; Summer Cypress
Russian Thistle
Field Bindweed
Red Ozier Dogwood
Rocky Mountain Juniper
Table 4, cont'd.
Cyperaceae Carex aquatilis Wahlenb.
Cyperaceae Carex athrostachya Olney
Cyperaceae Carex brevior (Dew3ey) Mackenzie
Cyperaceae Carex lanuginosa Michx.
Cyperaceae Carex lenticularis Michx.
Cyperaceae Carex microptera Mackenzie
Cyperaceae Carex multicostata Mackenzie
Cyperaceae Carex nebrascensis Dewey
Cyperaceae Carex sp.
Cyperaceae Cyperus aristatus Rottb.
N
N
N
N
N
N
N
N
N
N
N
N
N
N
X
N
N
N
N
N
N
N
N
X
N
N
N
N
X
X
X
X
X
N
N
N
N
N
N
N
N
N
N
N
N
0
N
X
N
N
N
N
N
N
N
N
X
N
N
N
X
X
X
X
X
N
N
N
N
N
N
N
N
N
N
N
N
N
N
X
N
N
N
N
N
N
N
N
X
N
N
N
N
X
X
X
X
X
153
Water Sedge
Slender beaked sedge
Short beaked sedge
Woolly Sedge
Kellog's Sedge
Small-winged Sedge
Many ribbed sedge
Nebraska Sedge
Sedge
Awned Flatsedge
Cyperaceae Eleocharis palustris (L.) Roemer & J.A. Schultes Spike Rush
Cyperaceae Scirpus maritimus L.
Seacoast bulrush
Cyperaceae Scirpus pungens Vahl
Three Square Bulrush
Cyperaceae Scirpus validus Vahl
Softstem Bulrush
Elaeagnaceae Elaeagnus angustifolia L.
Russian Olive
Elaeagnaceae Shepherdia argentea (Pursh) Nutt.
Thorn Buffaloberry
Equisetaceae Equisetum arvense L.
Common Horsetail
Equisetaceae Equisetum hyemale L.
Common Scouring Rush
Equisetaceae Equisetum laevigatum A. Braun
Smooth Scouring Rush
Equisetaceae Equisetum pratense Ehrh.
Horsetail
Equisetaceae Equisetum sylvaticum L.
Wood Horsetail
Equisetaceae Equisetum variegatum Scheich. Ex F. Weber & D.M.H. Mohr Variegated Horsetail
Equisetaceae Equisetum sp.
Horsetail
Euphorbiaceae Euphorbia esula L.
Leafy Spurge
Euphorbiaceae Euphorbia glyptosperma Engelm.
Ribseed sandmat; ridgeseed spurge
Fabaceae Glycyrrhiza lepidota Pursh
Wild Licorice
Fabaceae Hedasarum sp. L.
Sweetwetch; Hedysarum
Fabaceae Lupinus argenteus Pursh
Silvery lupine
Fabaceae Medicago lupulina L.
Black Medic; Hop Clover
Fabaceae Melilotus alba Medikus
White Sweet Clover
Fabaceae Melilotus officinalis (L.) Lam.
Yellow Sweet Clover
Fabaceae Melilotus sp. (alba/officinalis)
White or Yellow Sweet Clover
Fabaceae Melilotus sum (all Melilotus)
White, Yellow and sp. Sweet Clover
Pendent Pod Crazyweed
Lance leaf scurf pea
Strawberry Clover
Alsike Clover (pink)
Red Clover (deep red)
White Clover
American Vetch
Fumitory
Golden Currant
Western or Northern Black Currant
Redshoot Gooseberry
Gooseberry or currant
Silverleaf Phacelia
Wild Iris
Jointed Rush
Baltic Rush, Wire Rush
Toad Rush
Roundfruit Rush
Dagger-Leaf Rush, Rocky Mountain Rush
Inland Rush
Long-Syled Rush
Tuberous Rush
Slender Rush, Trail Rush
Torrey's Rush
Rush
Hemp Nettle
Ground Ivy
Cut Leaved Ragweed
Wild Mint (shusshua); Fieldmint
Catnip
Hedge Nettle
Nodding Onion
Wild Asparagus
N
N
X
X
X
X
N
X
N
N
N
N
N
N
N
N
N
X
N
N
N
N
N
N
N
X
X
N
N
X
N
N
X
N
N
X
X
X
X
N
X
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
X
X
N
N
X
N
0
X
N
N
X
X
X
X
N
X
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
X
X
N
N
X
N
N
X
154
Table 4, cont'd.
Fabaceae Oxytropis deflexa (Pallas) DC.
Fabaceae Psoralea lanceolata Pursh
Fabaceae Trifolium fragiferum L.
Fabaceae Trifolium hybridum L.
Fabaceae Trifolium pratense L.
Fabaceae Trifolium repens L.
Fabaceae Vicia americana Muhl. ex Willd
Fumariaceae Fumaria officianalis L.
Grossulariaceae Ribes aureum Pursh
Grossulariaceae Ribes hudsonianum Richards.
Grossulariaceae Ribes setosum Lindl.
Grossulariaceae Ribes sp.
Hydrophyllaceae Phacelia hastata Dougl. Ex Lehm.
Iridaceae Iris missouriensis Nutt.
Juncaceae Juncus articulatus L.
Juncaceae Juncus balticus Willd.
Juncaceae Juncus bufonius L.
Juncaceae Juncus compressus Jacq.
Juncaceae Juncus ensifolius Wikstr.
Juncaceae Juncus interior Wieg.
Juncaceae Juncus longistylis Torr.
Juncaceae Juncus nodosus L.
Juncaceae Juncus tenuis Willd.
Juncaceae Juncus torreyi Coville
Juncaceae Juncus sp.
Lamiaceae Galeopsis tetrahit L.
Lamiaceae Glechoma hederocea (?) L.
Lamiaceae Lycopus americanus Muhl. ex W. Bart.
Lamiaceae Mentha arvensis L.
Lamiaceae Nepeta cataria L.
Lamiaceae Stachys palustris L.
Liliaceae Allium cernuum Roth
Liliaceae Asparagus officinalis L.
N
N
N
N
N
N
N
N
N
N
N
N
N
X
N
N
N
X
N
N
X
N
X
X
X
N
N
X
X
N
X
N
N
N
X
N
X
N
N
0
N
X
X
N
N
N
0
N
N
both
N
N
N
N
X
N
X
N
X
N
N
X
N
X
X
X
N
N
X
X
N
X
N
N
N
X
N
X
N
X
X
X
0
N
0
X
N
N
N
N
N
X
N
X
N
155
Table 4, cont'd.
Liliaceae Smilacina stellata (L.) Dest.
Starry False Solomon's Seal
Marsileaceae Marsilea vestita Hook. & Grev.
Common Pepperwort; Clover fern
Oleaceae Fraxinus pennsylvanica Marsh
Green Ash
Onagraceae Epilobium minutum is E. paniculatum
(was mis-identified)
Onagraceae Epilobium paniculatum Nutt. ex Torr. & GrayTall Annual Willow-herb
Onagraceae Oenothera villosa Thunb.
Common Evening Primrose
Plantaginaceae Plantago eriopoda Torr.
Alkali plantain
Plantaginaceae Plantago major L.
Broadleaved Plantain
Poaceae Agropyron cristatum (L.) Gaertn.
Crested Wheatgrass
Poaceae Agrostis scabra Willd
Rough bentgrass
Poaceae Agrostis stolonifera L.
Redtop, Creeping Bentgrass
Stream Foxtail
Poaceae Alopecurus aequalis Sobol.
Poaceae Alopecurus arundinaceus Poir.
Garrison Creeping Foxtail
Poaceae Beckmannia syzigachne (Steud.) Fern.
American Sloughgrass
Poaceae Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths Blue grama
Poaceae Bromus inermis Leyss. ssp. inermis
Smooth Bromegrass
Poaceae Bromus inermis Leyss. ssp. pumpellianus
Smooth Bromegrass
Poaceae Bromus japonicus Thunb. ex Murr.
Japanese Bromegrass
Poaceae Bromus mollis aunct. non L.
Soft brome
Poaceae Bromus tectorum L.
Cheatgrass
Poaceae Calamagrostis stricta (Timm) Koel.
Northern Reedgrass
Poaceae Calamovilfa longifolia (Hook.) Schribn.
Prairie Sandreed
Poaceae Crypsis alopecuroides (Piller & Mitterp.) Schrad Lovegrass
Poaceae Dactylis glomerata L.
Orchard Grass
Poaceae Deschampsia cespitosa (L.) Beauv.
Tufted Hairgrass
Poaceae Echinochloa crus-galli (L.) Beauv.
Barnyard Grass
Poaceae Elymus canadensis L.
Canada Wild Rye
Poaceae Elymus cinereus Schribn. & Merr.
Great Basin WildRye, Giant WildRye
Poaceae Elymus elymoides (Raf.) Swezey
Bottle Brush, Squirrel Tail
Poaceae Elymus hispidus (Opiz) Melderis
Intermediate Wheatgrass
Poaceae Elymus lanceolatus(Scribn. & Sm.) Gould
Thickspike Wheatgrass
Poaceae Elymus repens (L.) Gould
Quackgrass
Poaceae Elymus smithii (Rydb.) Gould
Western Wheatgrass
Bluebunch Wheatgrass
Slender Wheatgrass
Lovegrass
Tall Fescue
Meadow Fescue
Foxtail Barley
Little Barley
Muhly
Western Grass
Reed Canary Grass
Timothy
Canada Bluegrass
Alkali Bluegrass
Fowl Bluegrass
Kentucky Bluegrass
Bluegrass (probably P. pratensis)
Yellow Bristlegrass or Foxtail
Green Bristlegrass or Foxtail
Alkali Cordgrass
Cordgrass
Dropseed
Needle and Thread Grass
Green Needlegrass
Polemonium
Smartweed
Water Smart Weed, Water Ladys Thumb
Prostrate knotweed
Black Bindweed
Douglas' Knotweed, Mountain Knotweed
Willow Weed, Curlytop Ladysthumb
Knotweed; Smartweed
Curly Dock
Golden Dock
N
N
N
X
X
N
N
N
N
N
X
X
N
N
N
(X)
X
X
N
N
N
N
N
N
N
N
X
X
N
N
N
0
N
X
X
N
N
N
N
X
X
N
N
X
X
X
X
X
N
N
N
N
N
N
N
N
N
X
N
X
N
N
N
X
X
N
N
N
N
N
X
X
N
N
N
N
X
X
N
N
N
N
N
N
N
N
N
X
N
X
X
N
X
N
X
N
156
Table 4, cont'd.
Poaceae Elymus spicatus (Pursh) Gould
Poaceae Elymus trachycaulus/sp. (Link) Gould ex Shinners
Poaceae Eragrostic hypnoides (Lam.) B.S.P.
Poaceae Festuca arundinacea Schreb.
Poaceae Festuca pratensis Huds.
Poaceae Hordeum jubatum L.
Poaceae Hordeum pusillum Nutt.
Poaceae Muhlenbergia racemosa (Michx.) B.S.P.
Poaceae Panicum capillare L.
Poaceae Phalaris arundinacea L.
Poaceae Phleum pratense L.
Poaceae Poa compressa L
Poaceae Poa juncifolia (?) Scribn.
Poaceae Poa palustris L.
Poaceae Poa pratensis L.
Poaceae Poa sp.
Poaceae Setaria glauca (L.) Beauv.
Poaceae Setaria viridis (L.) Beauv.
Poaceae Spartina gracilis Trin.
Poaceae Spartina pectinata Bose ex Link.
Poaceae Sporobolus cryptandrus (Torr.) Gray
Poaceae Stipa comata Trin. & Rupr.
Poaceae Stipa viridula Trin.
Polemoniaceae Polemonium sp.
Polygonaceae Polygonum achoreum Blake
Polygonaceae Polygonum amphibium L.
Polygonaceae Polygonum aviculare L.
Polygonaceae Polygonum convulvulus L.
Polygonaceae Polygonum douglasii Greene
Polygonaceae Polygonum lapathifolium L.
Polygonaceae Polygonum sp.
Polygonaceae Rumex crispus L.
Polygonaceae Rumex maritimus L.
Patience Dock
Narrowleaf Dock
Narrow-leaved or Willow Dock
Dock; Sorrel
Common purslane
Fringed Loosestrife
Wind Flower
White Virgin's Bower
Shore buttercup
Macoun's Buttercup
Blister Buttercup, Celery-leaved Buttercup
Tall Meadowrue
Agrimony
Juneberry; Serviceberry
Wild Strawberry
Large-Leaved Avens
Common Silverweed
Soft Cinquefoil
Norway Cinquefoil
Bushy cinquefoil
Chokecherry
Wild Rose
Wood's Rose
Wild Rose
Cleavers, Goose-grass
Thinleaf bedstraw
Lanceleaf or Rydberg's Cottonwood
Narrowleaf Cottonwood
Black Cottonwood, Balsam Poplar
Plains Cottonwood
Quaking Aspen; Trembling Aspen
Peachleaf Willow
Bebb Willow
X
X
N
0
N
X
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
X
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
X
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
157
Table 4, cont'd.
Polygonaceae Rumex patientia L.
Polygonaceae Rumex stenophyllus Ledeb.
Polygonaceae Rumex salicifolius Weinm.
Polygonaceae Rumex sp. (salicifolius or crispus)
Portulaceae Portulaca oleracea L.
Primulaceae Lysimachia ciliata L.
Ranunculaceae Anemone sp.
Ranunculaceae Clematis ligusticifolia Nutt.
Ranunculaceae Ranunculus cymbalaria Pursh
Ranunculaceae Ranunculus macounii Britt.
Ranunculaceae Ranunculus sceleratus L.
Ranunculaceae Thalictrum dasycarpum Fisch. & Ave-Lall.
Rosaceae Agrimonia striata Michx.
Rosaceae Amelanchier alnifolia (Nutt.) Nutt. ex M. Roemer
Rosaceae Fragaria vesca L.
Rosaceae Geum macrophyllum Willd.
Rosaceae Potentilla anserina (L.) Rydb.
Rosaceae Potentilla gracilis Dougl. ex Hook.
Rosaceae Potentilla norvegica L.
Rosaceae Potentilla paradoxa Nutt.
Rosaceae Prunus virginiana L.
Rosaceae Rosa sayi Schwein.
Rosaceae Rosa woodsii Lindl.
Rosaceae Rosa sp.
Rubiaceae Galium aparine L.
Rubiaceae Galium bifolium S. Wats.
Salicaceae Populus acuminata Rydb.
Salicaceae Populus angustifolia James
Salicaceae Populus balsamifera L.
Salicaceae Populus deltoides Bartr. ex Marsh.
Salicaceae Populus tremuloides Michx.
Salicaceae Salix amygdaloides Anderss.
Salicaceae Salix bebbiana Sarg.
Sandbar Willow
Diamond Willow, Yellow Willow
(possibly Bebb's?)
Mudwort
Dalmation Toad Flax
Yellow Monkey Flower
Mullein
American Speedwell
Water Speedwell, Water Pimpernel
Purslane Speedwell
Marsh speedwell
Henbane
Climbing Nightshade
Buffalo Bur
Hairy Nightshade
Cutleaved nightshade
Salt Cedar; Tamarisk
Broad-Leaved Cattail
Siberian Elm
Pennsylvania pellitory
Stinging nettle
Bracted Vervain
Blue Vervain
Violet
Virginia Creeper
Wild Grape
N
N
N
N
N
N
N
N
X
X
X
N
N
N
X
X
X
N
N
N
N
N
X
N
N
N
N
N
N
X
X
X
X
X
X
N
N
N
N
X
X
N
N
N
X
X
X
N
N
N
X
X
X
N
N
N
N
N
N
N
N
N
N
N
Most sp are N
N
0
N
N
N
N
158
Table 4, cont'd.
Salicaceae Salix exigua Nutt.
Salicaceae Salix lutea Nutt.
Salicaceae Salix sp. (small leaved willow)
Scrophulariaceae Limosella aquatica L.
Scrophulariaceae Linaria dalmatica (L.) P. Mill.
Scrophulariaceae Mimulus guttatus DC.
Scrophulariaceae Verbascum thapsus L.
Scrophulariaceae Veronica americana Schwein. ex Benth.
Scrophulariaceae Veronica anagallis-aquatica L.
Scrophulariaceae Veronica peregrina L.
Scrophulariaceae Veronica scutellata L.
Solanaceae Hyoscyamus niger L.
Solanaceae Solanum dulcamara L.
Solanaceae Solanum rostratum Dunal
Solanaceae Solanum sarrachoides auct. non Sendtner
Soanaceae Solanum triflorum Nutt.
Tamaricaceae Tamarix chinensis Lour.
Typhaceae Typha latifolia L.
Ulmaceae Ulmus pumila L.
Urticaceae Parietaria pensylvanica Muhl. ex Willd.
Urticaceae Urtica dioica L.
Verbenaceae Verbena bracteata Lag. & Rodr.
Verbenaceae Verbena hastata L.
Violaceae Viola sp.
Vitaceae Parthenocissus inserta (Kerner) Fritsch
Vitaceae Vitis riparia Michx.
UDA
UDA2
UEA
UIA
UJA
UJA2
UMA
UMA2
URA
USA
UWA
UXA
UXA2
Ungrazed Study Sites
Mile on river from Big Creek, MT
UCA
Table 5: Vegetation of ungrazed gravelbar sites: releve and frequency data. Species grouped by life form.
6.2
6.4
6.4
8.8
22
45.4
45.4
67
67
194
203
259
308
308
Avrg Stnd
Species Richness
# of non-native species/site
# of species/site
% non native species/site
7.9 5.6
17.6 12.0
46% 13%
SHRUBS
Percent non-native shrub spp
15%
Avrg # of non-native shrub spp
0.3
Tamarix chinensis
X
Elaeagnus angustifolia
X
N
N
N
N
1.2
1.5
7
4
3
3
3
14
22
7
6
5
12
14
5
5
13
11
11
11
5
31
49
14
12
19
26
28
10
7
54% 36%
Sum
27% 27% 60% 45%
45% 50%
50% 26% 46% 50% 50% 71%
Presence/Absence of species per site
Freq
9
5
0.21
0.07
3
1
0.79
0.29
0.07
0.07
11
4
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0.33
0
0
0
0
0
0.33
0.5
1
0
0
0
0
0
1
0
0
0
0
0
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
2
1
1
0
2
2
2
1
0
2
1
1
1
1
3
1
1
0
2
2
3
2
1
* Constancies calculated based on number of sites within the range of the species.
159
Species Constancy & Frequency
Native/Non-native Avrg ConTREES
N/X #/site stancy
Avrg # of non-native tree spp
0
Populus angustifolia
N
1.0*
Populus deltoides
N
1.0*
Avrg # of native tree species
1.0
Avrg # of tree species
1.0
Salix exigua
Salix amygdaloides
Amelanchier alnifolia
Vitis riparia
Avrg # of native shrub spp
Avrg # of shrub species
Number of Species at each site
#/site Dev
UIA
UJA
UJA2
UMA UMA2 URA USA UWA UXA UXA2
1.00
0.50
0.47
0.50
0.40
0.20
0.57
0.53
0.57
0.80
3
9
16
3
2
2
8
9
4
4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
160
Table 5. Ungrazed gravelbar sites - releve & frequency data, cont'd.
FORBS
Site UCA UDA UDA2 UEA
Percent non-native forb spp
57%
0.80 0.50 0.40 0.75
Avrg # of non-native forb spp
5.1
4
2
2
3
Taraxacum officinale
X
0.57
8
1
1
Melilotus officinalis
X
0.57
8
1
1
Melilotus alba
X
0.43
6
Chenopodium album
X
0.36
5
Medicago lupulina
X
0.36
5
Cirsium arvense
X
0.36
5
1
Centaurea maculosa
X
0.21
3
1
Sonchus uliginosus/S. asper
X
0.21
3
Polygonum aviculare
X
0.14
2
Sisymbrium loeselii
X
0.14
2
Rumex stenophyllus
X
0.14
2
Euphorbia esula
X
0.14
2
Chenopodium botrys
X
0.14
2
Verbascum thapsus
X
0.14
2
Tanacetum vulgare
X
0.14
2
Solanum dulcamara
X
0.14
2
Conium maculatum
X
0.07
1
Arctium minus
X
0.07
1
Filago arvensis
X
0.07
1
Cynoglossum officinale
X
0.07
1
1
Lepidium campestre
X
0.07
1
1
Thlaspi arvense
X
0.07
1
1
Silene noctiflora
X
0.07
1
Melilotus sp.
X
0.07
1
1
Trifolium repens
X
0.07
1
Artemisia biennis
X
0.07
1
Convolvulus arvensis
X
0.07
1
Rumex crispus
X
0.07
1
1
UIA
UJA
UJA2
UMA UMA2 URA USA UWA UXA UXA2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
161
Table 5. Ungrazed gravelbar sites - releve & frequency data, cont'd.
FORBS, cont'd.
Site UCA UDA UDA2 UEA
Rumex salicifolius
N
0.64
9
1
1
Plantago major
N
0.43
6
Verbena bracteata
N
0.36
5
Aster ascendens
N
0.21
3
1
1
Aster hesperius
N
0.21
3
Ranunculus sceleratus
N
0.21
3
Solidago gigantea
N
0.21
3
1
Oenethera villosa (=O.strigos N
0.21
3
Equisetum variegatum
N
0.21
3
Polygonum lapathifolium
N
0.21
3
Amaranthus albus
N
0.14
2
Potentilla norvegica
N
0.14
2
Rorippa palustris v. hispida
N
0.14
2
Ranunculus cymbalaria
N
0.14
2
Potentilla paradoxa
N
0.14
2
Sagittaria cuneata
N
0.07
1
Apocynum sibiricum
N
0.07
1
Cirsium undulatum
N
0.07
1
Arabis holboellii
N
0.07
1
1
Equisetum laevigatum
N
0.07
1
Glycyrrhiza lepidota
N
0.07
1
Polygonum douglasii
N
0.07
1
Polygonum sp.
N
0.07
1
1
Portulaca oleracea
N
0.07
1
Galium bifolium
N
0.07
1
Veronica americana
N
0.07
1
Gnaphalium palustre
N
0.07
1
Epilobium paniculatum
N
0.07
1
Mentha arvensis
N
0.07
1
Veronica anagallis-aquatica
N
0.07
1
Avrg # of native forb species
4.7
1
2
3
1
Avrg # of forb species
9.8
5
4
5
4
1
1
1
1
1
1
1
1
1
1
1
1
1
0
9
18
3
3
8
6
8
3
1
3
18
34
6
5
10
14
17
7
5
Table 5. Ungrazed gravelbar sites - releve & frequency data, cont'd.
GRAMINOIDS
Site UCA UDA UDA2 UEA
Percent non-ntv grmnd spp
36%
0.60 0.40 0.25 0.00
Avrg # of non-ntv grmnd spp
2.5
3
2
1
0
Poa pratensis
X
0.50
7
1
1
1
Phalaris arundinacea
X
0.36
5
Bromus tectorum
X
0.36
5
1
0
Alopecurus arundinaceus
X
0.29
4
Bromus inermis
X
0.29
4
1
1
Poa compressa
X
0.29
4
Elymus repens
X
0.29
4
Crypsis alopecuroides
X
0.07
1
Phleum pratense
X
0.07
1
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
0.43
0.43
0.29
0.29
0.21
0.21
0.21
0.14
0.14
0.07
0.07
0.07
0.07
0.07
0.07
0.07
2.9
5.4
6
6
4
4
3
3
3
2
2
1
1
1
1
1
1
1
1
1
1
1
1
UJA
UJA2
UMA UMA2 URA USA UWA UXA UXA2
0.00
0.44
0.46
0.67
0.67
0.50
0.44
0.57
0.00
0.00
0
4
6
4
4
3
4
4
0
0
1
1
1
1
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
162
Poa palustris
Carex sp.
Elymus trachycaulus/E. sp.
Agrostis stolonifera
Deschampsia cespitosa
Hordeum jubatum
Eleocharis palustris
Elymus elymoides
Alopecurus aequalis
Juncus sp.
Elymus smithii
Elymus cinereus
Eragrostis hypnoides
Hordeum pusillum
Juncus interior
Panicum capillare
Avrg # of ntv graminoid spp
Avrg # of graminoid species
UIA
1
1
1
1
1
1
1
1
1
1
1
1
2
3
3
5
0
5
7
2
2
3
5
3
0
0
5
5
4
5
0
9
13
6
6
6
9
7
0
0
Avrg cover of non-native spp
Average cover of species
% non native species
St Dev
0.0474
0.087
35%
FORBS
% cover of non-native forb spp
Avrg cover of non-native forb spp
Melilotus alba
Melilotus officinalis
Rumex stenophyllus
Cirsium arvense
Centaurea maculosa
Euphorbia esula
N
N
X
X
X
X
X
X
0.146
0.007
0.007
0
0
0
0
UXA2
UMA2
67 193.7
UXA
UMA
67
UWA
UJA2
45.4
USA
UJA
45.4
URA
UIA
22
203 258.5 308.2 308.2
0.003 0.026 0.080 0.079 0.067 0.024 0.039 0.026 0.139 0.135
0.225 0.190 0.247 0.098 0.084 0.310 0.141 0.082 0.179 0.135
1.3% 13.7% 32.4% 80.6% 79.8% 7.7% 27.7% 31.7% 77.7% 100%
0
0
0
0
0
0
0
0
0
0
0.073 0.032 0.070 0.046 0.220 0.001 0.001 0.003 0.002
0.001 0.008 0.001 0.030
0.073 0.032 0.070 0.046 0.220 0.001 0.001 0.003 0.002 0.001 0.008 0.001 0.030 0.000
0.073 0.032 0.070 0.046 0.220 0.001 0.001 0.003 0.002 0.001 0.008 0.001 0.030 0.000
0
0
0
0
0
0
0
0
0
0
0 0.045 1.000 1.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.002 0.044 0.046
0.002 0.044 0.046
0.047
0.011
0.058
0.064
0.226 0.027 0.009 0.001 0.002 0.025
0.559
0.019
0.011
0.003
0.001
0.001
0.000
0.000
1.000 0.000 0.500 0.875 1.000 0.524 0.234 0.500 0.000 0.333 0.724 0.231 0.905 1.000
0.013
0.115 0.004
0.260 0.080 0.011
0.001
0.031
0.226 0.027 0.009 0.001 0.002 0.140 0.004 0.013 0.000 0.261 0.080 0.042 0.000 0.000
0.226 0.027 0.009 0.001 0.002 0.140 0.004 0.013 0.000 0.261 0.080 0.044 0.044 0.046
0.004 0.000 0.003 0.007 0.003 0.011 0.022 0.002 0.000 0.011 0.021 0.003 0.095 0.089
0.003
0.002
0.002
0.001
0.001
0.004
0.090 0.057
0.006
0.004 0.030
0.011 0.006
0.001
0.004 0.002
0.001
0.004 0.001
0.004
0.002
163
Salix exigua
Salix amygdaloides
Avrg cover of native shrub spp
Average cover of shrub species
X
UEA
Avrg
Cover
6.2
6.4
6.4
8.8
ALL
Cover/Individual Site
0.046 0.008 0.001 0.004 0.007
0.158 0.311 0.067 0.089 0.057
34% 2.6% 1.5% 4.5% 12.3%
Native/Non-native AvCvr
TREES
N/X ALL
Avrg cover of non-native tree spp
0
Populus angustifolia (0.050, 9 sites)
N 0.032
Populus deltoides (0.008, 5 sites)
N 0.003
Avrgcover of native tree species
0.035
Average cover of tree species
0.035
SHRUBS
% cover of non-native shrub spp
Avrg cover of non-native shrub spp
Tamarix chinensis
UDA2
Ungrazed Study Sites
Mile on river from Big Creek, MT
UDA
UCA
Table 6. Vegetation of ungrazed gravelbar sites: releve and cover data. Species in order by life form, then by average cover.
Table 6. Vegetation of ungrazed gravelbar sites: releve and cover data, cont'd.
FORBS, cont'd.
UCA UDA UDA2 UEA UIA
UJA UJA2 UMA UMA2
Melilotus sp.
X 0.000
0.006
Taraxacum officinale
X 0.000
0.001
0.001 0.002
Chenopodium album
X 0.000
0.001
Tanacetum vulgare
X 0.000
0.003
Medicago lupulina
X 0.000
0.001
Polygonum aviculare
X 0.000
0.002
Sonchus uliginosus/S. asper
X 0.000
0.001
Verbascum thapsus
X 0.000
0.002
Silene noctiflora
X 0.000
0.002
Rumex crispus
X 0.000
0.001
Chenopodium botrys
X 0.000
0.001
Conium maculatum
X 0.000
0.001
Sisymbrium loeselii
X 0.000
0.001
Filago arvensis
X 0.000
Solanum dulcamara
X 0.000
N
N
N
N
N
N
N
N
N
N
N
X
N
N
N
N
0.004
0.001
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.001 0.001
0.003 0.034
USA
UWA UXA
0.001
0.001
0.001 0.001
0.001
0.001
0.001
0.001
0.001
0.001 0.007 0.004 0.001
0.004 0.005 0.001 0.001
0.001
0.001 0.011
0.009
0.001
0.001
0.001
0.006
0.003 0.003
0.003
0.001
0.001 0.004
0.004
0.003
0.003
0.003
0.001 0.001
0.001
UXA2
164
Rumex salicifolius
Plantago major
Rorippa palustris v. hispida
Mentha arvensis
Oenethera villosa
Polygonum lapathifolium
Solidago gigantea
Verbena bracteata
Amaranthus albus
Galium bifolium
Veronica americana
Portulaca oleracea
Potentilla norvegica
Aster ascendens
Potentilla paradoxa
Ranunculus cymbalaria
URA
0.001
0.002
0.002
Table 6. Vegetation of ungrazed gravelbar sites: releve and cover data, cont'd.
FORBS, cont'd.
UCA UDA UDA2 UEA UIA
UJA UJA2 UMA UMA2 URA USA UWA UXA UXA2
Ranunculus sceleratus
N 0.000
0.001
0.001
Equisetum variegatum
N 0.000
0.001
Veronica anagallis-aquatica
N 0.000
0.001
Sagittaria cuneata
N 0.000
0.001
Apocynum sibiricum
N 0.000
0.001
Aster hesperius
N 0.000
0.001
Cirsium undulatum
N 0.000
0.001
Equisetum laevigatum
N 0.000
0.001
Glycyrrhiza lepidota
N 0.000
0.001
Epilobium paniculatum
N 0.000
0.001
Polygonum sp.
N 0.000
0.001
Avrg cover of native forb species
0.010 0.000 0.001 0.003 0.001 0.000 0.010 0.072 0.002 0.003 0.022 0.008 0.010 0.010 0.000
Avrg cover of forb species
0.03 0.004 0.001 0.006 0.008 0.003 0.021 0.094 0.004 0.003 0.033 0.029 0.013 0.105 0.089
X
X
X
X
X
X
X
X
X
0.439
0.020
0.008
0.005
0.005
0.001
0.001
0.000
0.000
0.000
0.000
Deschampsia cespitosa
Agrostis stolonifera
Poa palustris
Hordeum jubatum
Carex sp.
N
N
N
N
N
0.006
0.001
0.001
0.001
0.001
0.500 0.143 0.250 0.000 0.000 0.536 0.392 0.987 0.848 0.867 0.750 0.875 0.000 0.000
0.004 0.001 0.001 0.000 0.000 0.015 0.058 0.077 0.067 0.013 0.018 0.021 0.000 0.000
0.012 0.029 0.061
0.011
0.004 0.019 0.044
0.004 0.024
0.003
0.001
0.005
0.012 0.005 0.018
0.004 0.003
0.002 0.002
0.001
0.003
0.001 0.001
0.001
0.001
0.001
0.002
0.001
0.076
0.011
0.007 0.007
0.004 0.004 0.002 0.001
0.001
0.003 0.004
0.001
0.001
0.002
0.001 0.004 0.001
165
GRAMINOIDS
% cover of non-native grmnd spp
Avrg cover of non-ntv grmnd spp
Agropyron repens
Alopecurus arundinaceus
Phalaris arundinacea
Poa pratensis
Poa compressa
Bromus inermis
Bromus tectorum
Phleum pratense
Crypsis alopecuroides
Table 6. Vegetation of ungrazed gravelbar sites: releve and cover data, cont'd.
GRAMINOIDS, cont'd.
UCA UDA UDA2 UEA UIA
UJA UJA2 UMA UMA2 URA USA UWA UXA UXA2
Eleocharis palustris
N 0.000
0.001
0.001 0.001
Agropyron trachycaulum/A. sp.
N 0.000
0.001
0.001
Alopecurus aequalis
N 0.000
0.001 0.001
Elymus elymoides
N 0.000
0.001 0.001
Juncus interior
N 0.000
0.001
Juncus sp.
N 0.000
0.001
Agropyron smithii
N 0.000
0.001
Avrg cvr of native graminoid spp
0.010 0.004 0.006 0.003 0.002 0.000 0.013 0.090 0.001 0.012 0.002 0.006 0.003 0.000 0.000
Avrg cover of graminoid species
0.030 0.008 0.007 0.004 0.002 0.000 0.028 0.148 0.078 0.079 0.015 0.024 0.024 0.000 0.000
166
Table 7: Gravel Measurements for Ungrazed Gravelbar Sites
SITE
All sites UCA UDA UEA UIA
UJA UMA UMA2 URA USA UWA UXA UXA2
River Mile
6.2
6.4
8.8 22.0 45.4 67.0 67.0 193.7 203 258.5 308.2 308.2
% Sand
17% 35% 11% 23%
5%
1% 23% 20%
4%
9%
1% 23% 35%
Gravel
10%
5.3
1
1
1
5
17
1
1
21
5
9
1
1
Size
25%
13.5
1
26
7
17
25
2
11
28
19
16
9
1
(width
median
38.1 49.5 72.5
33 42.5 46.5
18 54.5 42.5 38.5
25 21.5 13.5
in mm)
75%
61.5
90
100
50
75
60
38
99
59
66
40
32
29
90%
81.9 112
125
66
113
79
78
131
67
83
51
43
35
largest
127.3 180
145
87
189
128
155
221
104
123
74
57
65
167
Notes: A "1 mm" reading for gravel size means the substrate was sand.
"Percent sand" is the number of readings/100 which were sand instead of gravel.
River miles were measured beginning at upstream end of the study, just south of Emigrant, MT.
No data for UDA2 or UJA2; they were islands which became inaccessible when water level rose.
Salix exigua
All Sites
avrg st dev
161.5 146.5
9.7
2.0
6.8
2.4
2.1
0.7
111
40
1.8
1.8
8.1
0.4
1.20 1.09
0.99 1.13
0.065 0.078
53
17
35
13
12
5
0.51 0.36
* "Upriver" sites are those in the Populus angustifolia zone.
"Downriver" sites are in the Populus deltoides zone.
Salix exigua
Upriver sites*
avrg st dev
48.1 34.0
9.5
1.2
5.9
2.0
1.8
0.6
116
50
0.4
0.5
7.9
0.4
1.40 1.51
1.35 1.49
0.090 0.105
51
21
16
38
11
6
0.44 0.26
Salix exigua
Downriver*
avrg st dev
274.9 125.1
9.8
2.6
7.6
2.5
2.3
0.8
106
28
3.2
1.6
8.2
0.3
1.00 0.39
0.62 0.36
0.039 0.023
56
13
32
10
12
4
0.57 0.44
Populus
angustifolia
avrg st dev
48.4 37.9
11.2
2.3
7.7
2.7
2.4
0.8
111
48
0.4
0.5
7.8
0.2
2.85 1.15
2.80 1.15
0.168 0.065
36
14
49
12
15
4
0.45 0.22
Populus
deltoides
avrg st dev
304.9 129.7
16.7
5.5
14.3
5.6
4.4
1.7
153
38
3.4
1.6
8.1
0.3
2.26 1.04
1.86 0.96
0.123 0.069
42
20
38
12
20
10
0.47 0.24
168
Table 8. Environmental Variables at Ungrazed Sites
Gravelbar
Sandbar
Environmental variables
All Sites
All Sites
avrg st dev avrg st dev
River mile (from Big Creek)
110.4 106.6 205.3 162.4
Gage height (ft)
7.1
2.0
6.9
2.3
Height above water (ft)
4.7
2.1
4.6
2.4
Height above water (m)
1.4
0.6
1.4
0.7
Depth to gravel (cm)
28
24
CaCO3% Equiv
1.5
1.7
pH (1 to 1)
8.1
0.5
Total C%
0.56 0.23
% Organic C
0.37 0.06
Total N%
0.023 0.005
Sand %
72
11
Silt %
21
8
Clay %
7
3
EC mmhos/cm, 1 to 1
0.37 0.09
URB
UWB
UXB
UXB2
U2B
6.4
Stnd
#/site
Dev
11.4
6.9
25.1
8.3
43% 16%
UMB
Ungrazed Study Sites
Mile on river from Big Creek, MT
8.8 67.0
194
259
308
308
492
UEB
UDB
Table 9. Vegetation of ungrazed sandbar sites: releve & frequency data. Species grouped by life form.
Avrg
Species Richness
Average # of non-native species
Average # of species
% of species which are non native
SHRUBS
Percent non-native shrub species
Avrg number of non-native shrub species
Tamarix chinensis
Elaeagnus angustifolia
Salix exigua
Salix amygdaloides
Average number of native shrub spp.
Average number of shrub species
Con- Sum Presence/absence of species per site
stancy Freq
0
0
0
0
0
0
0
0.33*
1
1
1.00*
5
1
1
1
0.8
0
0
1
1
1
1
0.8
0
0
1
1
1
1
Avrg
#/site
35%
0.6
X
X
0.50
0.13
4
1
N
N
0.75
0.38
6
3
1.125
1.8
0
0
1
1
1
1
1
1
0
0
0
0
0 0.33 0.50 1.00 1.00
0
1
2
1
1
1
1
1
1
1
0
0
1
1
2
2
1
1
1
1
1
1
1
1
1
2
3
1
1
2
4
0
1
0
1
1
1
FORBS
Percent non-native forb species
45%
0.31 0.67 0.25 0.27 0.67 0.42 0.50 0.50
Avrg number of non-native forb species
8.6
4
20
1
3
14
11
10
6
Taraxacum officinale
X
0.50
4
1
1
1
1
Chenopodium glaucum
X
0.50
4
1
1
1
1
*Constancies calculated as a percentage of only those sites within their respective zones.
169
Species Constancy & Frequency
Native/Non-native
TREES
N/X
Avrg number of non-native tree species
Populus angustifolia
N
Populus deltoides
N
Average number of native tree species
Average number of tree species
Number of species at each site
4.0 22.0 3.0 7.0 20.0 13.0 12.0 10.0
25.0 35.0 10.0 23.0 34.0 31.0 24.0 19.0
16% 63% 30% 30% 59% 42% 50% 53%
170
Table 9. Vegetation of ungrazed sandbar sites: releve & frequency data, cont'd.
FORBS, cont'd.
UDB UEB UMB URB UWB UXB UXB2 U2B
Thlaspi arvense
X
0.50
4
1
1
1
1
Kochia scoparia
X
0.50
4
1
1
1
1
Chenopodium album
X
0.50
4
1
1
1
1
Medicago lupulina
X
0.50
4
1
1
1
1
Rumex crispus
X
0.50
4
1
1
1
1
Melilotus officinalis
X
0.38
3
1
1
1
Sisymbrium loeselii
X
0.38
3
1
1
1
Sonchus uliginosus/S. asper
X
0.38
3
1
1
1
Tanacetum vulgare
X
0.25
2
1
1
Amaranthus retroflexus
X
0.25
2
1
1
Chenopodium botrys
X
0.25
2
1
1
Descurainia sophia
X
0.25
2
1
1
Cirsium arvense
X
0.25
2
1
1
Verbascum thapsus
X
0.25
2
1
1
Filago arvensis
X
0.25
2
1
1
Lactuca seriola
X
0.25
2
1
1
Trifolium repens
X
0.13
1
1
Glecoma hederocea (?)
X
0.13
1
1
Cirsium vulgare
X
0.13
1
1
Asperugo procumbens
X
0.13
1
1
Cynoglossum officinale
X
0.13
1
1
Brassica rapa (=B. campestris)
X
0.13
1
1
Erysimum repandum
X
0.13
1
1
Amaranthus blitoides
X
0.13
1
1
Polygonum aviculare
X
0.13
1
1
Artemisia biennis
X
0.13
1
1
Lepidium perfoliatum
X
0.13
1
1
Rumex stenophyllus
X
0.13
1
1
Tragopogon dubius
X
0.13
1
1
Melilotus alba
X
0.13
1
1
Sisymbrium altissimum
X
0.13
1
1
Euphorbia esula
X
0.13
1
1
171
Table 9. Vegetation of ungrazed sandbar sites: releve & frequency data, cont'd.
FORBS, cont'd.
UDB UEB UMB URB UWB UXB UXB2 U2B
Gnaphalium palustre
N
0.50
4
1
1
1
1
Rorippa palustris v. hispida
N
0.50
4
1
1
1
1
Amaranthus albus
N
0.50
4
1
1
1
1
Xanthium strumarium
N
0.50
4
1
1
1
1
Ranunculus cymbalaria
N
0.38
3
1
1
1
Polygonum lapathifolium
N
0.38
3
1
1
1
Potentilla paradoxa
N
0.38
3
1
1
1
Epilobium paniculatum
N
0.25
2
1
1
Equisetum variegatum
N
0.25
2
1
1
Glycyrrhiza lepidota
N
0.25
2
1
1
Polygonum achoreum
N
0.25
2
1
1
Polygonum amphibium
N
0.25
2
1
1
Equisetum laevigatum
N
0.25
2
1
1
Verbena bracteata
N
0.25
2
1
1
Oenethera villosa
N
0.25
2
1
1
Iva xanthifolia
N
0.25
2
1
1
Aster hesperius
N
0.25
2
1
1
Polygonum douglasii
N
0.25
2
1
1
Galium bifolium
N
0.25
2
1
1
Solanum rostratum
N
0.25
2
1
1
Ranunculus sceleratus
N
0.13
1
1
Mimulus guttatus
N
0.13
1
1
Veronica americana
N
0.13
1
1
Mentha arvensis
N
0.13
1
1
Plantago major
N
0.13
1
1
Potentilla norvegica
N
0.13
1
1
Achillea millefolium
N
0.13
1
1
Equisetum arvense
N
0.13
1
1
Asclepias speciosa
N
0.13
1
1
Ranunculus Macounii
N
0.13
1
1
Helianthus annuus
N
0.13
1
1
Table 9. Vegetation of ungrazed sandbar sites: releve & frequency data, cont'd.
FORBS, cont'd.
UDB UEB UMB URB UWB UXB UXB2 U2B
Apocynum sibiricum
N
0.13
1
1
Verbena hastata
N
0.13
1
1
Erysimum asperum
N
0.13
1
1
Solidago occidentalis
N
0.13
1
1
Ambrosia psilostachya
N
0.13
1
1
Cicuta douglasii
N
0.13
1
1
Average number of native forb spp.
8.5
9
10
3
8
7
15
10
6
Average number of forb species
17.1
13
30
4
11
21
26
20
12
X
X
X
X
X
X
X
X
X
X
0.38
0.38
0.38
0.25
0.13
0.13
0.13
0.13
0.13
0.13
3
3
3
2
1
1
1
1
1
1
Eleocharis palustris
Carex sp.
Hordeum jubatum
Juncus ensifolius
Agrostis scabra
Poa juncifolia (?)
Juncus articulatus
Alopecurus aequalis
Juncus torreyi
Juncus bufonius
Juncus longistylis
N
N
N
N
N
N
N
N
N
N
N
0.88
0.25
0.25
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
7
2
2
1
1
1
1
1
1
1
1
44%
2.1
0 0.50 0.50 0.38 0.50 0.33 0.50 0.80
0
2
2
3
4
1
1
4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
172
GRAMINOIDS
Percent non-native graminoid species
Avrg # of non-native graminoid species
Agropyron repens
Bromus tectorum
Phalaris arundinacea
Echinochloa crus-galli
Alopecurus arundinaceus
Crypsis alopecuroides
Juncus compressus
Poa pratensis
Bromus japonicus
Bromus inermis
Table 9. Vegetation of ungrazed sandbar sites: releve & frequency data, cont'd.
GRAMINOIDS, cont'd.
UDB UEB UMB URB UWB UXB UXB2 U2B
Agrostis stolonifera
N
0.13
1
1
Carex lanuginosa
N
0.13
1
1
Scirpus maritimus
N
0.13
1
1
Scirpus validus
N
0.13
1
1
Eragrostis hypnoides
N
0.13
1
1
Carex nebrascensis
N
0.13
1
1
Juncus interior
N
0.13
1
1
Sporobolus cryptandrus
N
0.13
1
1
Average # of native graminoid species
3.4
10
2
2
5
4
2
1
1
Average number of graminoid species
5.5
10
4
4
8
8
3
2
5
173
174
Native/Non-native
TREES
N/X
Avrg cover of non-native tree spp
Populus deltoides (0.003, 5 sites)
N
Populus angustifolia (0.002, 3 sites)
N
Avrg cover of native tree species
Average cover of tree species
U2B
UXB2
UXB
UWB
URB
UMB
0.002 0.096 0.012 0.610 0.083 0.084 0.043 0.065
0.399 0.141 0.269 0.872 0.374 0.458 0.079 0.494
1% 68%
4% 70% 22% 18% 54% 13%
ALL
0
0.002
0.001
0.003
0.003
Salix exigua
N 0.090
Salix amygdaloides
N 0.002
Avrg cover of native shrub species
0.092
Average cover of shrub species
0.100
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
6.4
8.8 67.0 193.7 258.5 308.2 308.2 491.5
Cover/Individual Site
AvCvr
SHRUBS
% cover of non-native shrub spp
28%
Avrg cover of non-native shrub spp
0.008
Tamarix chinensis
X 0.008
FORBS
% cover of non-native forb species
Avrg cover of non-native forb spp
Chenopodium glaucum
Chenopodium album
Rumex stenophyllus
Thlaspi arvense
Rumex crispus (sp?)
Kochia scoparia
Polygonum aviculare
Taraxacum officinale
Lepidium perfoliatum
Melilotus officinalis
Cirsium arvense
Chenopodium botrys
Medicago lupulina
Lactuca seriola
Sonchus uliginosus/S. asper
Sisymbrium loeselii
Amaranthus blitoides
Filago arvensis
Artemisia biennis
Tanacetum vulgare
UEB
Avrg
Ungrazed Study Sites
Mile on River (from Big Creek, MT)
Cover
StDev ALL
Average cover of non-ntv spp 0.199 0.124
Average cover of species
0.245 0.386
% cover of non-native spp
28% 31%
UDB
Table 10. Vegetation of ungrazed sandbar sites: releve and cover data.
Species are in order by life form, and then by average cover.
38%
0.065
0.043
0.006
0.004
0.002
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0
0
0
0
0
0
0.007 0.005
0
0
0.003 0.002
0.005
0.000
0.000
0.005
0.007
0.005
0.000
0.003
0.002
0.000 0.000 0.005 0.007 0.005 0.000 0.003 0.002
0.000
0.000
0.000
0.143
0.062
1.000
1.000
0.000
0.000 0.000 0.000 0.012 0.005 0.027 0.017 0.000
0.012 0.005 0.027 0.017
0.320 0.004 0.010 0.072 0.074
0.014
0.334
0.240
0.002
0.004
0.010
0.072
0.076
0.000
0.000
0.240
0.334 0.004 0.010 0.084 0.081 0.027 0.017 0.240
0.091 0.794 0.018 0.695 0.898 0.129 0.333 0.100
0.002 0.054 0.002 0.330 0.053 0.055 0.015 0.008
0.008
0.330
0.032
0.001
0.003
0.011
0.003
0.028
0.003
0.001 0.015
0.002
0.001
0.007
0.001
0.007 0.002
0.009
0.001
0.001 0.003 0.003
0.007
0.001
0.005
0.001
0.003
0.001
0.003
0.001
0.003 0.000
0.001 0.003
0.003 0.000
0.001
0.001 0.001
0.002
0.001 0.001
0.002
0.001 0.001
175
Table 10. Vegetation of ungrazed sandbar sites: releve and cover data, cont'd.
UDB UEB UMB URB UWB UXB UXB2
FORBS, cont'd.
Asperugo procumbens
X 0.000
0.001
Erysimum repandum
X 0.000
0.001
Sisymbrium altissimum
X 0.000
Verbascum thapsus
X 0.000
0.001
Polygonum lapathifolium
N
Polygonum amphibium
N
Equisetum arvense
N
Xanthium strumarium
N
Verbena bracteata
N
Equisetum laevigatum
N
Solidago occidentalis
N
Aster hesperius
N
Galium bifolium
N
Iva xanthifolia
N
Potentilla paradoxa
N
Polygonum douglasii
N
Glycyrrhiza lepidota
N
Rorippa palustris v. hispida
N
Ranunculus cymbalaria
N
Gnaphalium palustre
N
Solanum rostratum
N
Polygonum achoreum
N
Epilobium paniculatum
N
Veronica americana
N
Amaranthus albus
N
Equisetum variegatum
N
Oenethera villosa
N
Helianthus annuus
N
Mentha arvensis
N
Potentilla norvegica
N
Cicuta douglasii
N
Ranunculus sceleratus
N
Average cover of native forb species
Average cover of forb species
0.033
0.009
0.008
0.006
0.006
0.006
0.005
0.005
0.004
0.003
0.002
0.002
0.002
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.096
0.161
0.118
U2B
0.001
0.140 0.003
0.001
0.067
0.060
0.015
0.034 0.001 0.001
0.001 0.048
0.045
0.040
0.037 0.002
0.033 0.001
0.020 0.001
0.001 0.016
0.001
0.001 0.015
0.006 0.006
0.003 0.003
0.002
0.002
0.004
0.004 0.001
0.002
0.001
0.004
0.001
0.001
0.001 0.005
0.004 0.001
0.004
0.001 0.001 0.001
0.001
0.001
0.001
0.001
0.002
0.001
0.001
0.001
0.001
0.020
0.014
0.111
0.145
0.006
0.372
0.030
0.072
0.022 0.068 0.113 0.475 0.059 0.427 0.045 0.080
176
Table 10. Vegetation of ungrazed sandbar sites: releve and cover data, cont'd.
UDB UEB UMB URB UWB UXB UXB2 U2B
GRAMINOIDS
% cover non-native graminoid spp
41% 0.000 0.609 0.071 0.876 0.109 0.500 0.786 0.331
Avrg cover of non-native grmnd spp 0.052 0.000 0.042 0.010 0.268 0.025 0.002 0.011 0.057
Echinochloa crus-galli
X 0.039
0.260
0.050
Elymus repens
X 0.007
0.041 0.010
0.001
Bromus tectorum
X 0.003
0.001
0.020 0.002
Bromus japonicus
X 0.001
0.011
Phalaris arundinacea
N 0.001
0.006 0.004
0.001
Bromus inermis
X 0.001
0.005
Crypsis alopecuroides
X 0.000
0.002
Juncus compressus
X 0.000
0.001
Eleocharis palustris
N
Carex nebrascensis
N
Carex lanuginosa
N
Scirpus maritimus
N
Eragrostis hypnoides
N
Juncus longistylis
N
Juncus ensifolius
N
Agrostis stolonifera
N
Alopecurus aequalis
N
Hordeum jubatum
N
Agrostis scabra
N
Sporobolus cryptandrus
N
Carex sp.
N
Juncus bufonius
N
Juncus articulatus
N
Poa juncifolia (sp?)
N
Avrg cover of native graminoid spp
Average cover of graminoid species
0.030
0.025
0.006
0.003
0.002
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.070
0.122
0.013 0.021 0.087 0.002 0.001 0.002
0.115
0.200
0.044
0.024
0.012
0.011
0.007
0.006
0.005
0.003
0.003
0.003
0.001
0.001
0.001
0.001
0.043
0.027
0.131
0.038
0.204
0.002
0.003
0.115
0.043 0.069 0.141 0.306 0.229 0.004 0.014 0.172
Species Constancy & Frequency
Native/Non-native Avrg
Con-
U2X
U1X
97 103 156 194 203 220 248 259 308 361 479 492
UYX
UNX2
97
UXX
UNX
67
UWX
UMX2
67
UUX
UMX
57
UTX
UKX2
58
USX
UKX
45
URX
UJX
23
UQX
UHX
6.4
UOX
UDX
6.2
Number of species at each site
Sum
8 11 6 7 7 3 7 9 11 14 14 13 11
11 22 11 28 14 14 17 24 20 31 28 21 18
9 11 10 11 6 11 12 7 13
22 29 25 21 13 24 40 31 21
73% 50% 55% 25% 50% 21% 41% 38% 55% 45% 50% 62% 61%
41% 38% 40% 52% 46% 46% 30% 23% 62%
Presence/absence of species per site
#/site stancy Freq
0.0
0
0.82*
0.27*
0.18*
0
0
9
3
2
0.6
0.6
SHRUBS
% non-native shrub species 10%
Avrg # of non-native shrub spp 0.5
Tamarix chinensis
X
0.55*
Elaeagnus angustifolia
X
0.36*
Artemisia absinthium
X
0.05
Salix exigua
Salix amygdaloides
Ribes aureum
Cornus stolonifera
Rosa sayi/Rosa woodsii
Ribes setosum
6
0
0
0
0
0
0
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
0
0
0
0
0
0
0
1
1
1
0
1
1
0
1
2
2
1
1
0
1
1
1
0
0
0
0
0
1
1
1
0
1
1
1
0
0
0
1
1
1
0
1
1
1
1
2
2
1
1
1
1
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.20 0.33 0.14 0.40 0.33 0.00 0.13 0.20 0.17 0.33
0
0
0
0
0
0
0
0
0
0
0
0
6
4
1
N
1.00 22
1
1
1
1
1
1 1
1
1
N
0.50 11
1
1 1
N
0.45 10
1 1
1
1
N
0.45 10
1
1 1
1
1
N
0.36
8
1
1
N
0.23
5
1
1
1
1
Symphoricarpos occidentalis
N
0.23
5
1
Ribes hudsonianum
N
0.14
3
1
1
Prunus virginiana
N
0.14
3
1
1
* Constancies calculated as a percentage of only those sits within their respective zones.
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
177
TREES
N/X
Avrg # of non-native tree spp
Populus deltoides
N
Fraxinus pennsylvanica
N
Populus angustifolia
N
Avrg # of native tree species
Avrg # of tree species
UCX
Ungrazed Study Sites
Mile on river from Big Creek, MT
Avrg Stnd
#/site Dev.
Species Richness
# of non-native spp
9.6
2.9
# of species
22.0
7.3
% non-native spp
46% 13%
UBX
Table 11. Vegetation of ungrazed Salix exigua (sandbar willow) sites: releve & frequency data. Species grouped by life form.
Salix sp. (small leaved willow)
Humulus lupulus
Amelanchier alnifolia
Toxicodendron rydbergii
Parthenocissus inserta
Avrg # of native shrub spp
Avrg # of shrub species
N
N
N
N
N
N
N
N
N
N
0.14
0.09
0.09
0.09
0.09
0.05
0.05
0.05
0.05
0.05
3
2
2
2
2
1
1
1
1
1
4.2
4.7
1
1
1
1
1
U2X
U1X
UYX
UXX
UWX
UUX
UTX
URX
UQX
UOX
UNX2
UNX
UMX2
UMX
UKX2
UKX
UJX
UHX
UDX
USX
1
1
1
1
1
1
1
1
1
1
1
1
1
5
5
1
1
3
3
2
2
6
6
6
6
10
10
4
4
6
6
5
5
2
2
4
5
2
3
12
14
3
5
2
3
1
1
7
8
4
5
5
6
2
3
0.80 0.57 0.67 0.38 0.75 0.20 0.63 0.67 0.70 0.58 0.65 0.78 1.00 0.40 0.67 0.36 0.54 0.57 0.60 0.33 0.22 0.82
0.91
0.68
0.55
0.41
0.41
0.36
0.27
0.27
0.27
0.23
0.18
0.18
0.18
0.18
0.18
0.18
0.14
0.14
20
15
12
9
9
8
6
6
6
5
4
4
4
4
4
4
3
3
4
1
8
1
1
1
1
1
4
1
1
1
5
6
1
1
5
1
1
1
1
1
1
1
1
1
1
1
1
8
1
1
1
1
1
7
1
1
1
1
1
1
1
1
11
1
1
1
11
1
1
1
7
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
7
1
1
6
1
1
1
1
1
1
5
1
7
1
1
4
1
1
1
6
1
1
1
1
1
1
7
1
1
1
1
1
4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
9
1
1
1
1
8
1
1
1
1
1
1
1
1
178
FORBS
Percent non-native forb specie 59%
Avrg # of non-native forb spp
6.4
Cirsium arvense
X
Taraxacum officinale
X
Sonchus uliginosus/S. asper
X
Cynoglossum officinale
X
Solanum dulcamara
X
Verbascum thapsus
X
Tanacetum vulgare
X
Conium maculatum
X
Tragopogon dubius
X
Cirsium vulgare
X
Arctium minus
X
Medicago lupulina
X
Silene noctiflora
X
Euphorbia esula
X
Melilotus officinalis
X
Sisymbrium loeselii
X
Nepeta cataria
X
Lactuca seriola
X
UCX
SHRUBS, cont'd.
Vitis riparia
Ribes sp.
Rhus trilobata
Juniperus scopulorum
Clematis ligusticifolia
UBX
Table 11. Vegetation of ungrazed Salix exigua sites: releve and frequency data, cont'd.
U2X
U1X
UYX
UXX
UWX
UUX
UTX
USX
URX
UQX
UOX
UNX2
UNX
UMX2
11
7
6
6
5
5
4
4
4
3
3
3
3
3
3
3
3
3
2
2
2
2
UMX
0.50
0.32
0.27
0.27
0.23
0.23
0.18
0.18
0.18
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.09
0.09
0.09
0.09
UKX2
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
UKX
Solidago gigantea
Equisetum laevigatum
Glycyrrhiza lepidota
Polygonum amphibium
Plantago major
Smilacina stellata
Mentha arvensis
Equisetum arvense
Potentilla paradoxa
Galium aparine
Potentilla gracilis
Lysimachia ciliata
Potentilla norvegica
Apocynum sibiricum
Ambrosia psilostachya
Solidago occidentalis
Verbena hastata
Verbena bracteata
Cicuta douglasii
Geum macrophyllum
Urtica dioica
Conyza canadensis
UJX
2
2
2
1
1
1
1
1
1
1
1
UHX
0.09
0.09
0.09
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
UDX
X
X
X
X
X
X
X
X
X
X
X
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
179
FORBS, cont'd.
Rumex crispus
Linaria dalmatica
Melilotus alba
Lychnis alba
Centaurea maculosa
Trifolium hybridum
Trifolium pratense
Lepidium perfoliatum
Artemisia biennis
Descurainia sophia
Chenopodium album
UCX
UBX
Table 11. Vegetation of ungrazed Salix exigua sites: releve and frequency data, cont'd.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
GRAMINOIDS
% of non-ntv grmnd spp
58%
Avrg # of non-ntv grmnd spp
2.7
Phalaris arundinacea
X
Poa pratensis
X
Elymus repens
X
0.09
0.09
0.09
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
U2X
U1X
UYX
UXX
UWX
UUX
USX
URX
UQX
UOX
UNX2
UNX
UMX2
UMX
UKX2
UKX
UJX
UHX
UDX
UCX
UTX
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
180
FORBS, cont'd.
Aster hesperius
N
Oenethera villosa
N
Xanthium strumarium
N
Cirsium undulatum
N
Thalictrum dasycarpum
N
Achillea millefolium
N
Iris missouriensis
N
Aster subspicatus
N
Vicia americana
N
Equisetum variegatum
N
Agrimonia striata
N
Potentilla anserina
N
Stachys palustris
N
Asclepias speciosa
N
Aster ascendens
N
Polygonum sp.
Parietaria pensylvanica
N
Polygonum lapathifolium
N
Equisetum hyemale
N
Ranunculus cymbalaria
N
Ranunculus Macounii
N
Equisetum sylvaticum
N
Heterotheca villosa
N
Lycopus americanus
N
Avrg # of native forb species
5.8
Avrg # of forb species
11.5
UBX
Table 11. Vegetation of ungrazed Salix exigua sites: releve and frequency data, cont'd.
1
1
1
1
1
1
1
1
1
2
5
7
14
3
6
10
13
2
8
4
5
3
8
4
12
4
10
8
19
6
17
2
9
0
7
9
15
5
12
10
14
8
13
3
7
5
10
14
21
14
18
5
11
0.80 1.00 0.50 0.18 0.25 0.67 0.67 0.50 0.80 0.50 0.50 0.67 0.75 0.67 0.50 0.50 0.75 0.50 0.80 0.33 0.33 0.50
4
0.73
0.68
0.59
16
15
13
1
1
3
1
1
2
1
1
2
1
1
1
1
2
2
1
1
1
1
1
1
4
1
1
1
3
1
3
1
1
6
1
1
1
3
1
1
2
1
1
1
1
3
1
1
1
3
1
1
1
2
1
1
4
1
1
1
4
1
2
3
1
1
1
1
Bromus tectorum
Phleum pratense
Dactylis glomerata
Bromus japonicus
Poa compressa
Juncus compressus
N
N
N
N
N
N
N
N
Elymus trachycaulus/A. sp. N
Spartina pectinata
N
Elymus lanceolatus
N
Eleocharis palustris
N
Hordeum jubatum
N
Carex lenticularis
N
Juncus nodosus
N
Carex arthrostachya
N
Juncus longistylis
N
Elymus elynoides
N
uncus sp.
N
Elymus cinereus
N
Sporobolus cryptandrus
N
Scirpus pungens
N
Avrg # of ntv graminoid specie
Avrg # of graminoid species
2.4
5.1
4
3
2
2
2
1
1
1
1
0.36
0.36
0.32
0.14
0.09
0.09
0.09
0.09
0.09
0.09
0.09
0.09
0.09
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
8
8
7
3
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
U2X
U1X
UYX
UXX
UWX
UUX
UTX
USX
URX
UQX
1
UOX
UMX2
UMX
UKX2
UKX
UJX
UHX
UDX
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
181
Agrostis stolonifera
Carex sp.
Poa palustris
Carex aquatilis
Carex lanuginosa
Deschampsia cespitosa
Juncus balticus
Carex microptera
0.18
0.14
0.09
0.09
0.09
0.05
0.05
0.05
UNX2
X
X
X
X
X
X
X
X
UNX
Alopecurus arundinaceus
UCX
GRAMINOIDS, cont'd.
Bromus inermis
UBX
Table 11. Vegetation of ungrazed Salix exigua sites: releve and frequency data, cont'd.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
2
9
3
1
1
1
1
3
3
3
1
1
1
3
1
2
1
1
1
8
5
3
4
11
4
3
3
2
5
6
6
9
4
3
2
6
4
4
5
12
4
3
6
6
Native/Non-native
U2X
U1X
97 103 156 194 203 220 248 259 308 361 479 492
UYX
97
UXX
UNX2
67
UWX
UNX
67
UUX
UMX2
57
UTX
UMX
58
USX
UKX2
45
URX
UKX
23
UQX
UJX
6
UOX
UHX
6
0.17 0.17 0.61 0.09 0.70 0.33 0.71 0.27 0.05 0.19 0.22 0.38 0.65 0.73 0.54 0.18 0.75 0.62 0.13 0.15 0.60 0.43
0.95 0.55 1.66 1.20 0.80 1.27 1.71 1.68 1.03 0.93 0.79 1.15 1.17 1.40 1.19 1.02 1.39 1.05 0.89 0.90 1.48 0.97
0.18 0.31 0.37 0.08 0.88 0.26 0.42 0.16 0.05 0.20 0.27 0.33 0.56 0.52 0.46 0.18 0.54 0.59 0.14 0.17 0.41 0.44
ALL
0.000
0.010
0.007
0.000
0.017
0.017
2%
0.015
X 0.012
X 0.003
X 0.000
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.21
0.00
0.00 0.11 0.01
0.00
0.01 0.02 0.01
0.00
0.00 0.00 0.00 0.21 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.11 0.01 0.00 0.00 0.00 0.00 0.01 0.02 0.01
0.00 0.00 0.00 0.21 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.11 0.01 0.00 0.00 0.00 0.00 0.01 0.02 0.01
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.14 0.00 0.01 0.00 0.07 0.00 0.20 0.00
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.10 0.00 0.00 0.00 0.05 0.00 0.17 0.00
0.09
0.17
0.00 0.00
0.05
0.01
N 0.506 0.71 0.32 0.73 0.38 0.06 0.57 0.64 0.42 0.79 0.53 0.51 0.59 0.51 0.54 0.54 0.53 0.57 0.38 0.33
N 0.055
0.26
0.04 0.18
0.01 0.14
0.00 0.00
0.29
N 0.016
0.00
0.13 0.03 0.09 0.00 0.09 0.01
0.01
N 0.011
0.06
0.18
N 0.011
0.23
0.00 0.01
Symphoricarpos occidentalis
Ribes aureum
N 0.010
0.04 0.00 0.11 0.00 0.05 0.00
0.00
0.00
0.00
Rosa woodsii/R. sayi
N 0.009
0.02
0.18
0.00
0.00
0.00
0.00
Prunus virginiana
N 0.005
0.00 0.11
0.00
Ribes sp.
N 0.003
0.06
*Sites with "0.00" cover had 0.001-0.004, i.e. 0.1-0.4% cover. P. angustifolia cover in UHX was a neighboring mature tree, not seedlings.
0.38 0.59 0.53
0.21 0.08 0.00
0.00
182
Salix exigua
Salix amygdaloides
Cornus stolonifera
Ribes hudsonianum
6
Cover/Individual Site
AvCvr
TREES
N/X
Avrg cvr of non-ntv tree spp
Populus angustifolia*
N
Populus deltoides*
N
Fraxinus pennsylvanica
N
Avrg cvr of native tree spp
Avrg cvr of all tree spp
SHRUBS
% cover non-ntv shrub spp
Avrg cvr non-ntv shrub spp
Elaeagnus angustifolia
Tamarix chinensis
Artemisia absinthium
UDX
Avrg
Cover
St dev ALL
Avrg cvr of non-ntv spp
0.243 0.394
Average cover of all spp
0.309 1.144
Non-ntv spp as % of ttl cvr 20% 34%
UCX
Ungrazed Study Sites
Mile on river from Big Creek, MT
UBX
Table 12. Vegetation of ungrazed Salix exigua (sandbar willow) sites, releve & cover data.
Species are in order by life form, then by average cover.
Salix sp. (small lvd willow)
Clematis ligusticifolia
Humulus lupulus
Vitis riparia
Ribes setosum
Rhus trilobata
Amelanchier alnifolia
Toxicodendron rydbergii
Juniperus scopulorum
Avrg cvr of all ntv shrub spp
Avrg cvr of all shrub spp
Sonchus uliginosus/asper
Taraxacum officinale
Verbascum thapsus
Arctium minus
Cirsium vulgare
Euphorbia esula
Sisymbrium loeselii
Conium maculatum
Silene noctiflora
Tragopogon dubius
Nepeta cataria
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
0.002
0.002
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.632
0.647
70%
0.133
0.073
0.013
0.012
0.012
0.010
0.002
0.002
0.002
0.002
0.002
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
U2X
U1X
UYX
UXX
UWX
UUX
UTX
USX
URX
UQX
UOX
UNX2
UNX
UMX2
UMX
UKX2
UKX
UJX
UHX
0.04
0.00
0.03
0.00
0.00
0.02
0.00
0.00 0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.71 0.34 0.73 0.68 0.06 0.90 0.85 1.34 0.79 0.67 0.53 0.73 0.51 0.54 0.57 0.53 0.58 0.38 0.66 0.60 0.68 0.53
0.71 0.34 0.73 0.68 0.06 0.90 0.85 1.34 0.79 0.67 0.53 0.73 0.51 0.54 0.66 0.53 0.58 0.38 0.71 0.60 0.85 0.53
1.00 0.31 0.92 0.64 0.96 0.86 0.99 0.81 0.15 0.85 0.90 0.73 1.00 0.92 0.81 0.18 0.86 0.89 0.11 0.21 0.31 1.00
0.02 0.02 0.51 0.06 0.19 0.08 0.34 0.27 0.01 0.09 0.12 0.05 0.05 0.16 0.28 0.06 0.27 0.03 0.01 0.01 0.01 0.30
0.02 0.01 0.51
0.19 0.08 0.33 0.00 0.01 0.05 0.07 0.03 0.04 0.15 0.00 0.03 0.06 0.02 0.00
0.00
0.00
0.29
0.26 0.00
0.22
0.00
0.00
0.00 0.02 0.00 0.00
0.00 0.00 0.00
0.00
0.01 0.01
0.00
0.20
0.00
0.05
0.03 0.01 0.00
0.00
0.02
0.00 0.00
0.00 0.00
0.00
0.01
0.01 0.00
0.00
0.00 0.00 0.00 0.01 0.01
0.00 0.00 0.01
0.00 0.00
0.00
0.00
0.00 0.00
0.02
0.03
0.00
0.00 0.01 0.01 0.00
0.00 0.00
0.01
0.00
0.00
0.00
0.00 0.00 0.00
0.01
0.00
0.00
0.00
0.00 0.00 0.00 0.00
0.00
0.01 0.00
183
FORBS
% cover of non-ntv forb spp
Avrg cvr of non-ntv forb spp
Cirsium arvense
Melilotus officinalis
Melilotus alba
Solanum dulcamara
Cynoglossum officinale
Trifolium hybridum
Tanacetum vulgare
N
N
N
N
N
N
N
N
N
UDX
Shrubs, cont'd.
UCX
UBX
Table 12. Vegetation of ungrazed Salix exigua sites, cover data - cont'd.
Oenethera villosa
Equisetum laevigatum
Heterotheca villosa
Geum macrophyllum
Verbena hastata
Galium aparine
Potentilla gracilis
Polygonum sp.
0.000
0.000
0.000
0.000
0.000
0.000
0.000
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
0.007
0.006
0.005
0.004
0.003
0.003
0.002
0.002
0.001
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.00
U2X
U1X
UYX
UXX
UWX
UUX
UTX
USX
URX
UQX
UOX
UNX2
UNX
UMX2
UMX
UKX2
UKX
UJX
UHX
UDX
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.02 0.04
0.04
0.02
0.01 0.01
0.06
0.00 0.00
0.00
0.00
0.08 0.00
0.08 0.04 0.00
0.09
0.00 0.00 0.06 0.00 0.00
0.06 0.01
0.01 0.00
0.03
0.00
0.00
0.00
0.01
0.00 0.02 0.01
0.01
0.00 0.01
0.00
0.00
0.02
0.01
0.00
0.00
0.01
0.01
0.00 0.00
0.01
0.01
0.01
0.00
0.01
0.00
0.00
0.00
0.00
0.00
0.00 0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00 0.00
0.00
0.00
184
Glycyrrhiza lepidota
Solidago gigantea
Solidago occidentalis
Equisetum hyemale
Smilacina stellata
Apocynum sibiricum
Lysimachia ciliata
Polygonum amphibium
Ambrosia psilostachya
Mentha arvensis
Aster ascendens
Equisetum arvense
Aster subspicatus
Plantago major
Asclepias speciosa
Verbena bracteata
Equisetum variegatum
Conyza canadensis
X
X
X
X
X
X
X
UCX
Forbs, cont'd.
Medicago lupulina
Lactuca seriola
Lychnis alba
Centaurea maculosa
Lepidium perfoliatum
Descurainia sophia
Rumex crispus
UBX
Table 12. Vegetation of ungrazed Salix exigua sites, cover data - cont'd.
N
N
N
N
N
N
N
N
N
N
Agrostis stolonifera
Poa palustris
Carex sp.
Carex aquatilis
Spartina pectinata
Elymus lanceolatus
Elymus trachycaulus/E. sp.
Deschampsia cespitosa
Carex lanuginosa
N
N
N
N
N
N
N
N
N
U2X
U1X
UYX
UXX
UWX
UUX
UTX
USX
URX
UQX
UOX
UNX2
UNX
UMX2
UMX
UKX2
UKX
UJX
UHX
UDX
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00 0.04 0.05 0.03 0.01 0.01 0.00 0.07 0.05 0.02 0.01 0.02 0.00 0.01 0.07 0.25 0.04 0.00 0.11 0.05 0.02 0.00
0.02 0.06 0.56 0.09 0.20 0.09 0.34 0.34 0.06 0.11 0.13 0.07 0.05 0.17 0.35 0.31 0.31 0.03 0.12 0.06 0.03 0.30
73%
0.246
0.200
0.025
0.017
0.003
0.001
0.001
0.000
0.000
0.69 1.00 0.27 0.15 0.94 0.90 0.73 0.00 0.25 0.60 0.76 0.92 1.00 0.99 0.93 0.68 0.96 0.92 1.00 0.58 0.72 0.98
0.019
0.014
0.010
0.007
0.004
0.002
0.002
0.002
0.001
0.07
0.15 0.15 0.10 0.03 0.51 0.25 0.38 0.00 0.04 0.09 0.10 0.33 0.60 0.57 0.16 0.12 0.47 0.59 0.06 0.14 0.42 0.13
0.51 0.23 0.37
0.11 0.08 0.07 0.03
0.04 0.06 0.03 0.00
0.02
0.00
0.02 0.16 0.58 0.52 0.16 0.11 0.47 0.59 0.01 0.11 0.42 0.13
0.02 0.09 0.08 0.02 0.00
0.01
0.02
0.10
0.00
0.03
0.00
0.01
0.05
0.00
0.00
0.00
0.05
0.00
0.02
0.02
0.01
0.00
0.01
0.01
0.00
0.08 0.13 0.01
0.02
0.03 0.14 0.00 0.13
0.19 0.00
0.01 0.06 0.02
0.00
0.02
0.00
0.00
0.00
0.00
0.16
0.09
0.05
0.04 0.01
0.04
0.00
0.02
0.00
185
GRAMINOIDS
% cvr non-ntv gramnd spp
Avrg cvr non-ntv gramnd spp
Phalaris arundinacea
X
Poa pratensis
X
Elymus repens
X
Bromus inermis
X
Alopecurus arundinaceus
X
Phleum pratense
X
Dactylis glomerata
X
Bromus tectorum
X
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.039
0.172
UCX
FORBS, cont'd.
Xanthium strumarium
Potentilla paradoxa
Equisetum sylvaticum
Circuta douglasii
Thalictrum dasycarpum
Iris missouriensis
Potentilla anserina
Parietaria pensylvanica
Polygonum lapathifolium
Aster hesperius
Avrg cvr of all native forb sp
Avrg cvr of all forb spp
UBX
Table 12. Vegetation of ungrazed Salix exigua sites, cover data - cont'd.
N
N
N
N
N
N
N
N
N
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.063
0.309
U2X
U1X
UYX
UXX
UWX
UUX
UTX
USX
URX
UQX
UOX
UNX2
UNX
UMX2
UMX
UKX2
UKX
UJX
UHX
UDX
UCX
GRAMINOIDS, cont'd.
Elymus elymoides
Carex microptera
Juncus nodosus
Sporobolus cryptandrus
Eleocharis palustris
Hordeum jubatum
Carex lenticularis
Juncus longistylis
Juncus sp.
Avrg cvr of ntv gramnd spp
Avrg cvr of graminoid spp
UBX
Table 12. Vegetation of ungrazed Salix exigua sites, cover data - cont'd.
0.01
0.01
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.07 0.00 0.27 0.18 0.03 0.03 0.14 0.00 0.13 0.06 0.03 0.03 0.00 0.00 0.01 0.06 0.02 0.05 0.00 0.10 0.16 0.00
0.22 0.15 0.37 0.21 0.54 0.28 0.52 0.00 0.17 0.15 0.13 0.36 0.60 0.57 0.18 0.18 0.49 0.64 0.06 0.24 0.58 0.13
186
Species Richness
Average # of non-native species
Average # of species
Percent non-native species
Avrg
Stnd
#/site
Dev
6.9
19.8
5.9
8%
UMN2
UNN
UNN2
58
0
66
67
0
58
97
0
51
97
0
53
UEN3
UKN
45
0
81
UCN2
UJN
9
0
49
Young
UEN2
6
9
0
0
35 c 50
6
0
5
9
0
5
Avrg Stnd
Number of species at each site
2.9
34%
UEN
Ungrazed Study Sites
Mile on river from Big Creek, MT
Percent cover of cow pies
Average DBH (cm), three largest trees
UCN
Mature
Table 13. Vegetation of ungrazed Populus angustifolia (narrowleaf cottonwood) sites:
Releve & frequency data. Species are in order by life form, then by constancy.
#/site
8
6
3
11
6
3
9
9
25
21
13
28
15
12
24
20
12
32% 29% 23% 39% 40% 25% 38% 45%
59%
Con-
Dev # spp/site
3
9
5
6
16
8
4% 56% 63%
Sum Pres/abs
stancy Freq
0
1
0.50
0.00
1
0
1
1
0
0
1
1
1
1
1
1
0
0
SHRUBS
Average # of non-natv shrub spp
Rosa sayi/R. woodsii
N
Symphoricarpos occidentalis
N
Ribes aureum
N
Juniperus scopulorum
N
Rhus trilobata
N
Ribes setosum
N
Cornus stolonifera
N
Clematis ligusticifolia
N
Prunus virginiana
N
Salix exigua
N
Ribes hudsonianum
N
0
0.88
0.75
0.63
0.50
0.50
0.50
0.50
0.25
0.25
0.13
0.13
7
6
5
4
4
4
4
2
2
1
1
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
0
1
1
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0.00
0.00
1 0.00
0.50
0.00
0.00
1 0.00
0.00
0.00
1.00
0.00
0
0
0
1
0
0
0
0
0
2
0
1
1
1
187
Species Constancy & Frequency
Native/Non-native Avrg Con- Sum Presence/absence of species per site
TREES
N/X #/site stancy Freq
Average # of non-native tree spp
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
Populus angustifolia
N
1.00
8
Fraxinus pennsylvanica
N
0.13
1
1
1
1
1
1
1
1
2
Average # of native tree species
1.1
Average # of tree species
1.1
1
1
1
1
1
1
2
7
1.00
0.75
0.38
6
6
2
2
4
4
0
0
0
8
6
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
1
1
0
0
3
3
0.36 0.57 0.33 0.54 0.50 0.40 0.38 0.42
4
4
2
7
2
2
5
5
7
1
1
1
1
1
1
1
6
1
1
1
1
1
1
3
1
1
1
1
1
1
3
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
UEN3
6
6
UCN2
UNN2
UNN
UMN2
UKN
0.00
0.00
0.71 0.80
5
4
1
1
1
1
0.50
0.50
0.00
0.00
0.00
0.50
0.50
0.50
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1.00
0.50
0.50
0
0
0
1
1
1
0
0
0
0
0
0
0
2
1
1
0.00
0.00
0.00
0
0
0
1
1
1
1
1
1
1
188
N
N
N
0.88
0.75
0.38
0.38
0.25
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.00
0.00
0.00
3
3
1
10
10
1
8
8
44%
3.9
UJN
1
1
5.3
5.3
FORBS
Percent of non-native forb spp
Average # of non-native forb spp
Cirsium arvense
X
Taraxacum officinale
X
Arctium minus
X
Tanacetum vulgare
X
Conium maculatum
X
Cynoglossum officinale
X
Verbascum thapsus
X
Melilotus sp.
X
Trifolium hybridum
X
Sonchus uliginosus/S. asper
X
Melilotus officinalis
X
Cirsium vulgare
X
Tragopogon dubius
X
Euphorbia esula
X
Polygonum convulvulus
X
Centaurea maculosa
X
Artemisia biennis
X
Salsola kali
X
Smilacina stellata
Solidago gigantea
Glycyrrhiza lepidota
0.13
0.13
UEN2
N
N
UEN
SHRUBS, cont'd.
Shepherdia argentea
Salix amygdaloides
Average # of native shrub spp
Average # of shrub species
UCN
Table 13. Vegetation of ungrazed P. angustifolia sites - releve and frequency data, cont'd.
GRAMINOIDS
Percent of non-native grass spp
Avrg # of non-native grass spp
Poa pratensis
Phalaris arundinacea
Bromus inermis
Elymus repens
Alopecurus arundinaceus
Dactylis glomerata
Agropyron cristatum
5.0
8.9
1.00
0.63
0.50
0.25
0.25
0.25
0.13
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
7
4
6
6
13
2
4
3
5
8
13
0.00
0.00
0.00
0.00
0.00
0.00
0.50
0.50
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.50
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
1
7
12
0.80 0.29 0.33 1.00 1.00 0.25 0.80 1.00
4
2
1
4
4
1
4
4
8
1
1
1
1
1
1
1
1
5
1
1
1
1
1
1
1
1
1
4
2
1
1
2
1
1
2
1
1
1
1
0.50
0.00
0.50
1.00
0.50
0.00
0.00
UEN3
UCN2
UNN2
UNN
UMN2
UKN
1
UJN
1
1
1
7
11
68%
3.0
X
X
X
X
X
X
X
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
0
UEN2
0.25
0.25
0.25
0.25
0.25
0.25
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.13
0.00
UEN
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
1
1
189
FORBS, cont'd.
Equisetum laevigatum
Mentha arvensis
Geum macrophyllum
Urtica dioica
Apocynum sibiricum
Equisetum pratense
Fragaria vesca
Polygonum sp.
Achillea millefolium
Equisetum sp.
Vicia americana
Iris missouriensis
Plantago major
Potentilla norvegica
Galium aparine
Potentilla gracilis
Rudbeckia laciniata
Oxytropis deflexa
Average # of native forb spp
Average # of forb species
UCN
Table 13. Vegetation of ungrazed P. angustifolia sites - releve and frequency data, cont'd.
1
2
7
1
5
0.67 1.00
4
1
1
1
0
1
2
1
0
0
1
1
1
1
1.5
4.5
0.00
0.50
0.00
0.00
0.50
0.00
0.00
1
1
1
1
5
1
5
7
2
3
0
4
0
4
3
4
1
5
0
4
0
1
0
0
1
0
0
UEN3
1
UCN2
1
UNN2
UKN
1
1
UJN
1
1
1
1
UNN
3
2
2
2
1
1
1
UMN2
0.38
0.25
0.25
0.25
0.13
0.13
0.13
UEN2
N
N
N
N
N
N
N
UEN
GRAMINOIDS, cont'd.
Elymus trachycaulus/A. sp.
Agrostis stolonifera
Elymus smithii
Carex sp.
Elymus canadensis
Carex microptera
Juncus balticus
Avrg # of native grass species
Average # of grass species
UCN
Table 13. Vegetation of ungrazed P. angustifolia sites - releve and frequency data, cont'd.
1
1
2
6
0
1
190
UKN
UMN2
UNN
UNN2
58
0
66
67
0
58
97
0
51
97
0
53
AvCvr
Young
AvCvr
StDev
Avrg cvr of non-ntv spp
Avrg cover of species
% cvr of non-native spp
Mature
0.228
1.680
10% 14%
Cover/Individual Site
UEN3
UJN
45
0
81
UCN2
UEN2
9
0
49
Young
UEN
6
9
0
0
35 c 50
UCN
Ungrazed Study Sites
Mile on river from Big Creek, MT
Percent cover of cow pies
Avrg DBH (cm), three largest trees
Mature
Table 14. Vegetation of ungrazed Populus angustifolia (narrowleaf cottonwood) sites, releve
and cover data. Species are in order by life form, and then by average cover.
6
0
5
9
0
5
Cover/Site
0.170
0.217 0.029 0.027 0.476 0.210 0.116 0.432 0.313
0.244 0.035 0.453
0.258
1.150 1.650 1.695 1.901 2.046 1.682 1.627 1.688
0.821 0.544 1.098
SHRUBS
% cvr of non-native shrub spp
Avrg cvr of non-ntv shrub spp
N
Symphoricarpos occidentalis
Cornus stolonifera
N
Juniperus scopulorum
N
Rosa sayi/R. woodsii
N
Rhus trilobata
N
Shepherdia argentea
N
Salix amygdaloides
N
Ribes aureum
N
Ribes setosum
N
0%
0
0.151
0.102
0.096
0.049
0.019
0.017
0.015
0.014
0.005
2%
2%
25%
10%
7%
27%
19%
0.238
6%
41%
0
0
AvCvr
Young
0
0
0
0
0
0
0
0
0.600 0.960 0.840 1.000 0.800 0.920 0.840 0.960
0.120
0
0.573 0.506 0.640
0.000
0.600 0.960 0.840 1.000 0.800 0.920 0.960 0.960
0.573 0.506 0.640
0.600 0.960 0.840 1.000 0.800 0.920 0.960 0.960
0.573 0.506 0.640
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000
0.002 0.070
0.022 0.610 0.500 0.004
0.000
0.201 0.081
0.207 0.326
0.000
0.032 0.210 0.111 0.001 0.004
0.000
0.013 0.342 0.412
0.003 0.034
0.000
0.030 0.096 0.022
0.000
0.133
0.000
0.120
0.000
0.002
0.104
0.003
0.016 0.020
0.002
0.000
0.000
191
Native/Non-native AvCvr
TREES
N/X Mature
Avrg cvr of non-ntv tree spp
0
Populus angustifolia
N 0.865
Fraxinus pennsylvanica
N 0.015
Avrg cover of native tree spp
0.880
Avrg cover of tree species
0.880
19%
0.001
UEN3
UCN2
Young
UNN2
UNN
UMN2
UKN
UJN
UEN2
UEN
SHRUBS, cont'd.
Ribes hudsonianum
N 1E-04
Prunus virginiana
N 1E-04
Salix exigua
N
0
Avrg cover of ntv shrub spp
0.467
Avrg cover of shrub species
0.467
UCN
Mature
Table 14. Vegetation of ungrazed Populus angustifolia sites: releve and cover data, cont'd.
0.000
0.001
0.000
0.001
0.001
0.182 0.547 0.434 0.391 1.026 0.611 0.214 0.330
0.001 0.000 0.001
0.182 0.547 0.434 0.391 1.026 0.611 0.214 0.330
0.001 0.000 0.001
FORBS
% cover non-native forb spp
Avrg cover of non-ntv forb spp
Cirsium arvense
X
Arctium minus
X
Tanacetum vulgare
X
Taraxacum officinale
X
Centaurea maculosa
X
Conium maculatum
X
Melilotus sp.
X
Trifolium hybridum
X
Tragopogon dubius
X
Euphorbia esula
X
Cynoglossum officinale
X
46%
0.063
0.040
0.013
0.009
0.001
0
3E-04
1E-04
1E-04
1E-04
1E-04
1E-04
0.057 0.037 0.010 0.871 0.901 0.508 0.857 0.462
71%
0.009 0.001 0.002 0.230 0.091 0.033 0.066 0.073
0.005 0.006 0.003
0.006
0.058 0.090 0.032 0.062 0.070
0.001
0.100
0.000
Smilacina stellata
Glycyrrhiza lepidota
Solidago gigantea
Apocynum sibiricum
Rudbeckia laciniata
Equisetum pratense
Polygonum sp.
Urtica dioica
0.023
0.022
0.012
0.005
0.005
9E-04
1E-04
4E-04
0.142 0.025 0.003 0.003 0.006 0.003 0.001
0.070
0.001 0.001 0.002
0.002
0.000
0.001
0.002 0.001
0.001 0.001
0.001
0.000
192
N
N
N
N
N
N
N
N
0.002
1.000 0.429
0.003 0.005
0.001
0.001
0.001
0.001
0.001
0.000
0.001
0.000
0.001
0.000
0.152
0.003
0.001
0.000
0.042 0.030
0.000
0.004 0.017
0.000
0.012 0.004 0.001
0.000
0.041
0.000
0.036
0.000
0.003 0.004
0.000
0.003
0.000
0.001
0.002
0.004
Agrostis stolonifera
Elymus smithii
N
N
Elymus trachycaulus/E. sp.
N
Juncus balticus
N
Carex microptera
N
Elymus canadensis
N
Carex sp.
N
Avrg cvr of ntv graminoid spp.
Avrg cover of graminoid spp
0.028
0.007
0.002
5E-04
3E-04
0
1E-04
UEN3
UCN2
0.000
0.000
0.001
0.000
0.001
0.000
0.001
0.000
0.001
0.000
0.001
0.000
0.001
0.000
0.068 0.149 0.026 0.198 0.034 0.010 0.032 0.011 0.085
0.131 0.158 0.027 0.200 0.264 0.101 0.065 0.077 0.158
79%
0.164
0.053
0.049
0.046
0.013
0.004
3E-04
0
Young
UNN2
UNN
UMN2
UKN
UJN
UEN2
UEN
0.001 0.001
0.001
0.002 0.000 0.004
0.007 0.006 0.007
0.990 0.241 0.113 1.000 1.000 0.965 0.973 1.000
95%
0.208 0.028 0.025 0.246 0.119 0.083 0.366 0.240
0.240 0.029 0.450
0.214 0.001
0.078 0.130
0.906 1.000
0.000
0.114 0.028 0.025 0.018 0.001 0.083 0.112 0.014
0.006 0.011
0.090
0.005 0.009
0.010 0.090
0.174
0.004
0.096
0.004 0.027
0.229 0.008 0.450
0.000
0.002
0.000
0.001 0.001
0.080 0.144
0.001 0.001
0.004 0.052
0.000
0.002 0.010
0.004
0.000
0.000
0.002
0.000
0.001 0.002
0.001
0.000
0.037 0.002 0.088 0.196 0.000 0.000 0.003 0.010 0.000
0.002 0.003 0.000
0.202 0.210 0.116 0.221 0.246 0.119 0.086 0.376 0.240
0.241 0.032 0.450
193
GRMINOIDS
% cvr of non-ntv grmnd spp
Avrg cvr of non-ntv gram. spp
Phalaris arundinacea
X
Poa pratensis
X
Bromus inermis
X
Elymus repens
X
Dactylis glomerata
X
Agropyron cristatum
X
Alopecurus arundinaceus
X
3E-04
1E-04
1E-04
1E-04
1E-04
1E-04
1E-04
1E-04
UCN
FORBS, cont'd.
Equisetum laevigatum
N
Achillea millefolium
N
Equisetum sp.
N
Vicia americana
N
Mentha arvensis
N
Geum macrophyllum
N
Galium aparine
N
Plantago major
N
Avrg cover of ntv forb species
Avrg cover of forb species
Mature
Table 14. Vegetation of ungrazed Populus angustifolia sites: releve and cover data, cont'd.
N
N
N
N
N
N
0.59
0.53
0.47
0.41
0.41
0.35
U4P
U2P
U2P2
U1P2
U1P
UZP2
UZP
10
14
15
13
10
10
5
5
7
10
7
6
6
6
6
3
8
9
19
33
23
25
29
19
15
13
11
28
14
16
14
20
17
10
23
15
53% 42% 65% 52% 34% 53% 33% 38% 64% 36% 50% 38% 43% 30% 35% 30% 35%
60%
0
1
1
0
1
0
1
1
0
1
1
0
1
2
2
1
1
2
2
2
2
1
1
0.00 0.13 0.33 0.22 0.18 0.13 0.00 0.25 1.00 0.13 0.50 0.50 0.50 0.10 0.00 0.20 0.11
0
13
4
10
9
8
7
7
6
1
1
1
2
1
1
2
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
0
1
1
0
0
0
0
0
1
1
1
2
2
1
1
2
2
1
1
2
2
1
1
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
0
1
1
1
0.5
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
194
Rosa sayi/R. woodsii
Vitaceae Vitis riparia
Clematis ligusticifolia
Toxicodendron rydbergii
Cornus stolonifera
UYP
0
2
Species Constancy & Frequency
Native/Non-native Avrg Con- Sum Presence/absence of species per site
TREES
N/X #/site stancy Freq
Avrg # of non-native tree spp
0
0 0 0 0 0
0 0 0
1
1
1
1
1
1
1
1
Populus deltoides
N
1.00
17
1
Fraxinus pennsylvanica
N
0.47
8
1
1
1
1
1
1
2
1
Avrg # of native tree species
1.5
Avrg number of tree species
1.5
1
1
1
1
1
1
2
1
Symphoricarpos occidentalis
UXP
492
Number of species at each site
8.3 3.4
19.4 6.6
43% 11%
SHRUBS
Percent of non-ntv shrub spp
25%
Avrg # of non-native shrub spp
1.0
Elaeagnus angustifolia
X
0.76
Artemisia absinthium
X
0.24
UWP2
UWP
UVP
USP2
USP
URP2
URP
UPP
203 252 259 259 308 361 372 372 479 479 492 510
0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
82 72 76 65 33 112 54 40 56 50 38 44 41 71 75 36 73
103 144 194 194 203
Avrg Stnd
#/site Dev
Species Richness
Avrg # of non-native species
Avrg # of species
% non-native species
UOP
Ungrazed Study Sites
Mile on river from Big Creek, MT
Percent cover cow pies
Diameter at breast height (cm), 3 largest trees
Mature
Table 15. Vegetation of ungrazed Populus deltoides (Plains cottonwood) sites: releve and frequency data.
Species grouped by life form, then in order by constancy.
FORBS, cont'd.
Percent of non-ntv forb spp
Avrg # of non-native forb spp
Taraxacum officinale
Medicago lupulina
Cirsium arvense
Solanum dulcamara
Arctium minus
Melilotus officinalis
Melilotus alba
Euphorbia esula
Nepeta cataria
Sonchus uliginosus/S. asper
Chenopodium album
Cynoglossum officinale
5
5
4
4
3
3
3
3
1
1
1
1
4.8
5.8
X
X
X
X
X
X
X
X
X
X
X
X
0.65
0.59
0.35
0.29
0.24
0.24
0.18
0.18
0.18
0.18
0.18
0.18
11
10
6
5
4
4
3
3
3
3
3
3
1
1
1
1
1
1
1
1
1
1
1
U2P
U4P
U2P2
U1P2
U1P
UZP2
UZP
UYP
UXP
UWP2
UWP
UVP
USP2
1
1
USP
UPP
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
53%
4.3
URP2
0.29
0.29
0.24
0.24
0.18
0.18
0.18
0.18
0.06
0.06
0.06
0.06
URP
N
N
N
N
N
N
N
N
N
N
N
N
8
9
2
3
0.64 0.50 0.75 0.73 0.36 0.86 0.33 0.20 0.67 0.47 0.50 0.40 0.67 0.50 0.50 0.50 0.50
0.57
7
1
1
7
8
9
1
1
1
4
6
9
1
1
1
1
1
1
7
9
8
1
1
9
11
4
1
1
1
7
8
6
1
1
1
3
4
1
0
1
2
1
7
8
7
1
1
1
1
1
1
1
1
4
4
1
1
1
1
1
2
4
1
2
2
1
1
2
9
10
2
3
1
1
1
7
7
2
4
5
1
5
4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
195
SHRUBS, cont'd.
Shepherdia argentea
Ribes aureum
Salix amygdaloides
Prunus virginiana
Rhus trilobata
Juniperus scopulorum
Ribes setosum
Parthenocissus inserta
Salix exigua
Artemisia dracunculus
Artemisia cana
Artemisia frigida
Avrg # of native shrub species
Avrg number of shrub species
UOP
Table 15. Vegetation of ungrazed Populus deltoides sites: releve and frequency data, cont'd.
U2P
U4P
U2P2
1
U1P2
1
U1P
UZP2
1
1
1
1
UZP
10
7
5
4
4
4
3
2
2
2
2
2
2
1
1
1
1
1
1
1
1
UYP
0.59
0.41
0.29
0.24
0.24
0.24
0.18
0.12
0.12
0.12
0.12
0.12
0.12
0.06
0.06
0.06
0.06
0.06
0.06
0.06
1
UXP
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
1
UWP2
Apocynum sibiricum
Smilacina stellata
Glycyrrhiza lepidota
Solidago gigantea
Asclepias speciosa
Galium aparine
Parietaria pensylvanica
Plantago major
Solidago occidentalis
Equisetum hyemale
Aster ascendens
Violaceae Viola sp.
Ambrosia psilostachya
Solidago mollis
Equisetum variegatum
Rumex salicifolius
Equisetum laevigatum
Mentha arvensis
Lactuca pulchella
Solanum sarrachoides
1
1
UWP
1
1
UVP
1
USP2
2
2
2
2
2
1
1
1
1
1
USP
0.12
0.12
0.12
0.12
0.12
0.06
0.06
0.06
0.06
0.06
URP2
UPP
X
X
X
X
X
X
X
X
X
X
URP
FORBS, cont'd.
Tanacetum vulgare
Verbascum thapsus
Sisymbrium loeselii
Asparagus officinalis
Melilotus sp.
Centaurea maculosa
Cirsium vulgare
Salsola kali
Conium maculatum
Polygonum convulvulus
UOP
Table 15. Vegetation of ungrazed Populus deltoides sites: releve and frequency data, cont'd.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
196
1
1
1
1
Agrostis stolonifera
Elymus canadensis
Elymus trachycaulus/E. sp.
Cyperaceae Carex sp.
Calamovilfa longifolia
Muhlenbergia racemosa
Elymus lanceolatus
Spartina pectinata
Avrg # of native grass species
Avrg number of grass species
0.06
0.06
0.06
0.06
0.06
0.00
0.00
3.6
7.9
X
X
X
X
X
X
X
X
0.76
0.76
0.59
0.53
0.18
0.06
0.06
0.06
13
13
10
9
3
1
1
1
N
N
N
N
N
N
N
N
0.24
0.24
0.18
0.18
0.18
0.12
0.06
0.06
4
4
3
3
3
2
1
1
U2P
U4P
U2P2
U1P2
U1P
UZP2
UZP
UYP
UXP
UWP2
UWP
UVP
USP2
USP
URP2
1
1
1
1
1
1
1
4
11
78%
3.0
1.2
4.2
URP
1
1
1
1
1
0
0
5
10
3
7
0.60 0.67 1.00 0.75 0.67 1.00 0.67 1.00 0.67 0.67 1.00 0.43 0.43 1.00 0.80 1.00 1.00
1
4
3
1
1
1
9
18
4
1
1
1
1
3
12
4
1
1
1
1
3
11
3
1
1
7
11
4
1
1
1
1
1
7
3
1
1
1
2
3
4
1
1
1
1
4
5
3
1
1
1
1
3
4
1
1
1
8
15
2
1
4
8
2
1
3
5
3
1
1
1
1
3
3
1
1
1
3
6
2
4
1
2
2
4
1
2
1
1
1
1
1
1
1
1
1
1
1
1
0
1
0
2
0
4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
5
2
6
0
4
1
4
2
6
0
3
2
6
0
3
2
6
1
3
0
2
1
4
7
4
7
0
2
1
5
197
GRAMINOIDS
% of non-ntv grass spp
Avrg # of non-native grass spp
Poa pratensis
Bromus inermis
Agropyron repens
Phalaris arundinacea
Alopecurus arundinaceus
Festuca arundinacea
Dactylis glomerata
Poa compressa
N
N
N
N
N
N
N
UPP
FORBS, cont'd.
Polygonum sp.
Lysimachia ciliata
Asclepias verticillata
Anemone sp.
Lonicera sp.
Polygonum lapathifolium
Xanthium strumarium
Avrg # of native forb species
Avrg number of forb species
UOP
Table 15. Vegetation of ungrazed Populus deltoides sites: releve and frequency data, cont'd.
URP2
USP
USP2
UVP
UWP
UWP2
UXP
UYP
UZP
UZP2
U1P
U1P2
U2P2
U4P
U2P
AvCvr
URP
StDev
UPP
Ungrazed Study Sites
Mile on river from Big Creek, MT
Percent cover cow pies
DBH (cm), 3 largest trees Avrg: 60
UOP
Table 16. Vegetation of ungrazed Populus deltoides (Plains cottonwood) sites; releve and cover data.
Species are in order by life form, then by average cover.
103
144
194
194
203
203
252
259
259
308
361
372
372
479
479
492
510
492
0
82
0
72
0
76
0
65
0
0
33 112
0
54
0
40
0
56
0
50
0
38
0
44
0
41
0
71
0
75
0
36
0
73
0
2
0.12
Cover/Individual Site
Average cover of non-ntv spp
0.207
0.423 0.34 0.42 0.80 0.67 0.24 0.18 0.44 0.54 0.65 0.28 0.47 0.68 0.13 0.12 0.32 0.60 0.32
Average cover of species
0.301
1.563 1.65 1.63 1.43 2.11 1.22 2.14 1.46 1.15 1.38 1.53 1.41 1.84 1.35 1.67 1.11 1.65 1.85
1.05
14%
28% 0.20 0.26 0.56 0.32 0.20 0.09 0.30 0.47 0.47 0.18 0.33 0.37 0.10 0.07 0.29 0.36 0.17
0.11
% cover non-native species
Toxicodendron rydbergii
N 0.0784
Symphoricarpos occidentalis
N 0.0472
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00
1.00 0.96 0.12 0.84 0.80 1.00 0.96 0.51 0.72 0.96 0.92 1.00 1.00 0.52 0.44 0.92 0.96
0.93
0.01
0.01
0.00 0.15
0.00 0.02
1.00 0.96 0.12 0.84 0.80 1.00 0.97 0.51 0.72 0.97 0.92 1.00 1.00 0.67 0.44 0.92 0.98
0.93
1.00 0.96 0.12 0.84 0.80 1.00 0.97 0.51 0.72 0.97 0.92 1.00 1.00 0.67 0.44 0.92 0.98
0.93
0.00 0.59 0.60 0.43 0.03 0.02 0.00 0.65 1.00 0.38 1.00 1.00 1.00 0.11 0.00 0.00 0.26
0.00 0.21 0.63 0.44 0.00 0.02 0.00 0.16 0.12 0.15 0.14 0.36 0.05 0.11 0.00 0.00 0.19
0.21 0.63 0.43 0.00
0.16 0.12 0.15 0.14 0.36 0.05 0.11
0.19
0.00
0.00
0.02 0.00 0.02
0.57
0.00 0.06
0.00
0.16
0.22 0.02
0.01
0.27
0.00
0.03
0.01
0.23 0.17
Juniperus scopulorum
N 0.0392
0.41 0.26
Rosa sayi/R. woodsii
N 0.0152 0.02
0.04
0.08
0.01
0.09
Vitis riparia
N 0.0124
0.00 0.00 0.01
0.00
0.16
Cornus stolonifera
N 0.0108
0.00 0.02 0.00
0.08
Rhus trilobata
N 0.0106
0.06
0.02
0.10
Shepherdia argentea
N 0.0084
0.08
0.06 0.00
Clematis ligusticifolia
N 0.0081
0.00 0.05 0.01 0.00
0.06
Note: An entry of "0.00" for cover means there was cover present, but it was less than 0.005 (0.5%) for that site.
0.29
0.09
0.02
0.00 0.03
0.08
0.00
0.01
0.00
198
Native/Non-native AvCvr
TREES
N/X ALL
Avrg cover of non-ntv tree spp
0
Populus deltoides
N 0.802
Fraxinus pennsylvanica
N 0.012
Average cover of ntv tree spp
0.813
Average cover of tree spp
0.813
SHRUBS
% cover of non-ntv shrub spp
42%
Avrg cvr of non-ntv shrub spp
0.152
Elaeagnus angustifolia
X 0.1495
Artemisia absinthium
X 0.0022
0.0077
0.03 0.00
0.02
U2P
U4P
U2P2
U1P2
U1P
UZP2
UZP
UYP
UXP
UWP2
UWP
UVP
USP2
USP
URP2
URP
UPP
SHRUBS, cont'd.
Salix amygdaloides
N
Parthenocissus inserta
N
Ribes aureum
N
Salix exigua
N
Artemisia dracunculus
N
Ribes setosum
N
Prunus virginiana
N
Solanum sarrachoides
N
Artemisia frigida
N
Avrg cover of native shrub spp
Average cover of shrub spp
UOP
Table 16. Vegetation of ungrazed Populus deltoides sites: releve and cover data, cont'd.
0.08
0.01
0.0072
0.10 0.01
0.01 0.10 0.00 0.01
0.0069
0.06
0.0038
0.00
0.04
0.0024
0.00
0.0012
0.01
0.00
0.0006
0.01
0.01 0.00
0.01
0.0005
0.00
6E-05
0.261
0.04 0.14 0.42 0.59 0.10 0.90 0.04 0.09 0.00 0.24 0.00 0.00 0.00 0.86 0.34 0.13 0.53
0.00
0.412
0.04 0.35 1.05 1.03 0.11 0.92 0.04 0.25 0.12 0.40 0.14 0.36 0.05 0.97 0.34 0.13 0.72
0.00
0.40 0.42 0.14 0.80 0.44 0.73 0.00 0.00 0.07 0.73 0.14 0.00 0.86 0.10 0.17 0.00 0.44
0.01 0.07 0.01 0.00 0.01 0.14 0.00 0.00 0.00 0.10 0.00 0.00 0.01 0.00 0.00 0.00 0.02
0.06
0.11
0.11
0.00
0.11
0.00
0.00
0.09 0.00
0.01 0.00
0.00 0.03
0.00 0.00 0.00 0.00
0.00
0.01
0.00 0.00
0.01
0.00
0.00
0.00
0.00
0.00
0.00
0.00 0.00 0.00
0.00
0.01
0.01
0.01
0.00 0.00
0.00
0.00 0.00
0.00 0.00
0.00
0.00
0.00 0.00
0.00
0.00 0.00
0.00
199
FORBS
% cover of non-ntv forb spp
32%
Avrg cover of non-ntv forb spp
0.022
Euphorbia esula
X 0.004
Arctium minus
X 0.006
Solanum dulcamara
X 0.006
Cirsium arvense
X 0.003
Taraxacum officinale
X 0.001
Melilotus officinalis
X 0.000
Medicago lupulina
X 0.000
Melilotus alba
X 0.000
Melilotus sp.
X 0.000
Nepeta cataria
X 0.000
Verbascum thapsus
X 0.000
Chenopodium album
X 0.000
Sonchus uliginosus/asper
X 0.000
Tanacetum vulgare
X 0.000
Cirsium vulgare
X 0.000
Sisymbrium loeselii
X 0.000
Polygonum convulvulus
X 0.000
U2P
U4P
U2P2
U1P2
U1P
UZP2
UZP
UYP
UXP
UWP2
UWP
UVP
USP2
USP
URP2
URP
0.00
X
0.000
N
0.005
N
0.005
N
0.005
0.00
N
0.003
0.00 0.00
N
0.002
0.02
N
0.001
0.00
N
0.001
0.00
N
0.001
N
0.000
N
0.000
N
0.000
N
0.000
0.00
0.00
N
0.000
0.00
0.00
N
0.000
N
0.000
N
0.000
N
0.000
N
0.000
N
0.000
N
0.000
N
0.000
N
0.000
N
0.000
0.08
0.00
0.08
0.05 0.01 0.00
0.01
0.00
0.02
0.01
0.00
0.01
0.00
0.00
0.01
0.01
0.00
0.00
0.02
0.00 0.01
0.00
0.01
0.00 0.00
0.00
0.00
0.01
0.00
0.00
0.00
200
Parietaria pensylvanica
Solidago mollis
Apocynum sibiricum
Smilacina stellata
Glycyrrhiza lepidota
Solidago gigantea
Asclepias speciosa
Anemone sp.
Galium aparine
Aster ascendens
Asclepias verticillata
Solidago occidentalis
Equisetum hyemale
Violaceae Viola sp.
Ambrosia psilostachya
Lonicera sp.
Equisetum variegatum
Mentha arvensis
Polygonum lapathifolium
Polygonum sp.
Lysimachia ciliata
Plantago major
Xanthium strumarium
Average cover of ntv forb spp
Average cover of forb spp
UPP
FORBS, cont'd.
Cynoglossum officinale
UOP
Table 16. Vegetation of ungrazed Populus deltoides sites: releve and cover data, cont'd.
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.024
0.02 0.10 0.09 0.00 0.01 0.05 0.01 0.01 0.01 0.04 0.03 0.00 0.00 0.01 0.01 0.00 0.02
0.00
0.046
0.03 0.17 0.10 0.01 0.02 0.19 0.01 0.01 0.01 0.14 0.03 0.00 0.01 0.01 0.01 0.00 0.04
0.11
89%
0.56 0.99 1.00 0.94 0.78 1.00 1.00 1.00 1.00 0.97 1.00 0.68 0.26 1.00 0.98 1.00 1.00
0.250
0.33 0.14 0.16 0.23 0.23 0.03 0.44 0.38 0.53 0.03 0.32 0.33 0.08 0.02 0.32 0.60 0.11
X
0.147
0.31 0.00
X
0.043
0.01 0.11 0.02 0.22
X
0.040
X
0.017
X
0.002
X
0.000
X
0.000
N
0.018
Elymus canadensis
N
Calamovilfa longifolia
N
Agrostis stolonifera
N
Muhlenbergia racemosa
N
Cyperaceae Carex sp.
N
Spartina pectinata
N
Average cover of ntv grass spp
Average cover of grass spp
0.013
Elymus trachycaulus/E. sp.
0.26 0.26 0.10
0.01 0.12
0.00 0.00
0.32 0.32 0.06 0.01 0.15 0.60 0.11
0.18 0.03
0.10 0.01 0.07 0.12 0.24
0.01
0.000
0.01
0.00
0.01
0.00
0.00
0.04
0.00
0.00
0.25
0.00
0.03 0.02
0.00
0.00
0.03 0.19
0.09 0.00
0.00
0.01 0.07
0.01
0.00
201
0.000
0.000
0.00
0.01 0.01 0.01 0.00 0.14 0.01 0.10 0.00
0.006
0.005
0.00 0.01 0.01 0.13
U2P
U4P
U2P2
U1P2
U1P
UZP2
UZP
UYP
UXP
UWP2
UWP
UVP
USP2
USP
URP2
URP
UPP
GRAMINOIDS, cont'd.
% cover of non-ntv grass spp
Avrg cvr of non-ntv grass spp
Bromus inermis
Poa pratensis
Elymus repens
Phalaris arundinacea
Poa compressa
Alopecurus arundinaceus
Festuca arundinacea
UOP
Table 16. Vegetation of ungrazed Populus deltoides sites: releve and cover data, cont'd.
0.00
0.00
0.00
0.00
0.25 0.00 0.00 0.01 0.07 0.00 0.00 0.00 0.00 0.00 0.00 0.15 0.22 0.00 0.01 0.00 0.00
0.00
0.292 0.58 0.14 0.16 0.24 0.30 0.03 0.44 0.38 0.53 0.03 0.32 0.48 0.29 0.02 0.32 0.60 0.11
0.01
0.042
Table 17. Comparison of cover, richness and percent non-native species across ungrazed riparian plant communities.
Vegetation Type
Tree
All Communities
Richness/all sites
0
3
#
Ntv
Total
#
Forb
% Non # Non
Ntv
Ntv
#
Ntv
Total
#
Graminoid
% Non # Non
#
Ntv
Ntv
Ntv
Total
#
33%
15%
15%
2
4
0.3
1.2
0.007 0.058
6
1.5
0.064
47%
27
30
57
57%
5.1
4.7
9.8
56% 0.019 0.011 0.030
64%
36%
44%
16
9
2.5
2.9
0.020 0.010
25
5.4
0.030
50%
35%
28%
2
2
0.6
1.2
0.008 0.092
4
1.8
0.100
48%
34
37
71
45%
8.6
8.5
17.1
38% 0.065 0.096 0.161
36%
44%
41%
10
18
2.1
3.4
0.052 0.070
28
5.5
0.122
14%
10%
2%
3
18
0.5
4.2
0.015 0.632
21
4.7
0.647
39%
29
46
75
59%
6.4
5.1
11.5
70% 0.133 0.039 0.172
33%
58%
73%
11
22
2.7
2.4
0.246 0.063
33
5.1
0.309
0%
0%
0%
0
13
0
5.3
0 0.467
13
5.3
0.467
46%
18
21
39
44%
3.9
5
8.9
46% 0.063 0.068 0.131
50%
68%
79%
7
7
3.0
1.5
0.164 0.038
14
4.5
0.202
10%
25%
42%
2
18
1.0
4.8
0.152 0.261
20
5.8
0.412
47%
22
25
47
53%
4.3
3.6
7.9
32% 0.022 0.024 0.046
50%
78%
89%
8
8
3.0
1.2
0.250 0.042
16
4.2
0.292
39%
27%
11%
3
24
27
49
78
127
15
40
* No non-native tree species were found. Elaeagnus angustifolia was classified as a shrub, per the USDA on-line plants database.
55
202
X* Total
Gravelbar (n = 14)
Richness/all sites
0
2
Richness/each site
0
1.0
Cover
0 0.035
Sandbar (n = 8)
Richness/all sites
0
2
Richness/each site
0
0.8
Cover
0 0.003
Salix exigua (n = 22)
Richness/all sites
0
3
Richness/each site
0
0.6
Cover
0 0.017
Populus angustifolia (n = 8)
Richness/all sites
0
2
Richness/each site
0
1.1
Cover
0
0.88
Populus deltoides (n = 17)
Richness/all sites
0
2
Richness/each site
0
1.5
Cover
0 0.813
Shrub
% Non # Non
Ntv
Ntv
Table 17. Comparison of cover, richness and percent non-native species across ungrazed riparian plant communities, cont'd.
Vegetation Type
All Communities
Richness/all sites
# Non
Ntv St Dev
#
Ntv
Total
#
St Dev
50%
46%
34%
N/A
13%
35%
45
N/A
7.9
5.6
0.046 0.047
45
9.7
0.113
90
N/A
17.6
12
0.159 0.087
44%
43%
31%
N/A
16%
28%
46
N/A
11.3
6.9
0.125 0.199
59
13.9
0.261
105
N/A
25.2
8.3
0.386 0.245
33%
46%
35%
N/A
13%
20%
43
N/A
9.6
2.9
0.394 0.243
89
12.3
0.72
132
N/A
22
7.3
1.114 0.309
37%
34%
14%
N/A
8%
10%
25
6.9
0.227
N/A
2.9
0.17
43
12.9
1.453
68
N/A
19.8
5.9
1.680 0.258
38%
43%
28%
N/A
11%
14%
32
N/A
8.3
3.4
0.424 0.207
53
11.1
1.139
85
N/A
19
6.6
1.563 0.301
33%
N/A
68
N/A
139
207
N/A
203
Gravelbar (n = 14)
Richness/all sites
Richness/each site
Cover
Sandbar (n = 8)
Richness/all sites
Richness/each site
Cover
Salix exigua (n = 22)
Richness/all sites
Richness/each site
Cover
Populus angustifolia (n = 8)
Richness/all sites
Richness/each site
Cover
Populus deltoides (n = 17)
Richness/all sites
Richness/each site
Cover
SUMMARY
% Non
Ntv St Dev
Table 18. Species occurring with 20% or less constancy, across ungrazed riparian plant communities.
Plant
Number of low
Total # of
% low
community
constancy species species constancy
Gravelbars
54
91
59%
Sandbars
56
105
53%
Salix exigua
102
130
78%
P. angustifolia
30
68
44%
P. deltoides
53
85
62%
Average, all plant communities:
59.5%
Plant
community
Gravelbars
Salix exigua
P. angustifolia
P. deltoides
Trees
0
0
0
0
3
0
1
0
0
0
Shrubs
2
1
0
1
12
1
4
0
8
0
Forbs
20
20
17
16
40
19
11
10
19
16
204
Sandbars
Origin
Native
Non-Native
Native
Non-Native
Native
Non-Native
Native
Non-Native
Native
Non-Native
Percent low % of spp in
constancy
veg type
which are
which are
Gramnds TOTALS non-native non-native
9
31
2
23
43
50%
16
33
6
23
41
44%
19
73
8
28
28
33%
3
19
1
11
37
37%
6
33
4
20
38
38%
Table 19. Non-native species found in riparian plant communities, both ungrazed and grazed sites. Grouped by families.
Scientific name
** N = native, X = non-native (exotic), 0 = no data, both = depends on species or sub-species
205
Common name
UM* FPNW USDA
Asteraceae Sonchus uliginosus (Bieb.)/S. asper (L.) Hill
Marsh Sow Thistle
N/X** X/X X/X
Amaranthaceae Amaranthus blitoides S. Wats.
Prostrate Pigweed
N
N
X
Amaranthaceae Amaranthus retroflexus L.
Pigweed amaranth; rough pigweed
N
N
X
Apiaceae Conium maculatum L.
Poison Hemlock
X
X
X
Apiaceae Heracleum sphondylium L.
Cow Parsnip
N
0
X
Asteraceae Arctium minus Bernh.
Common Burdock
X
X
X
Asteraceae Artemisia absinthium L.
Sageweed; Absinthium
X
X
X
Asteraceae Artemisia biennis Willd.
Biennial Wormweed
N
N
X
Asteraceae Centaurea maculosa auct. non Lam.
Spotted Knapweed
X
X
X
Asteraceae Cirsium arvense (L.) Scop.
Canada Thistle
X
X
X
Asteraceae Cirsium vulgare (Savi) Ten.
Bull Thistle
X
X
X
Asteraceae Filago arvensis L.
Fluffweed
X
X
X
Asteraceae Lactuca serriola L.
Prickly Lettuce
X
X
X
Asteraceae Tanacetum vulgare L.
Common Tansy
X
X
X
Asteraceae Taraxacum officinale G. H. Weber ex Wiggers Common Dandelion
X
X
X
Asteraceae Tragopogon dubius Scop.
Goatsbeard
X
X
X
Boraginaceae Asperugo procumbens L.
Catchweed
X
X
X
Boraginaceae Cynoglossum officinale L.
European Hound's Tongue
X
X
X
Brassicaceae Alyssum alyssoides (L.) L.
Alyssum
X
X
X
Brassicaceae Brassica rapa L.
Field Mustard
X
X
X
Brassicaceae Camelina microcarpa DC.
Hairy False Flax
X
X
X
Brassicaceae Capsella bursa-pastoris (L.) Medik.
Shepherd's Purse
X
X
X
Brassicaceae Descurainia sophia(L.) Webb ex Prantl
Flixweed
X
X
X
Brassicaceae Erysimum repandum L.
Bushy wallflower
X
X
Brassicaceae Lepidium campestre (L.) R. Br.
Field Pepper Grass
X
X
X
Brassicaceae Lepidium perfoliatum L.
Clasping Pepper Grass
X
X
X
* UM = http://invader.dbs.umt.edu (Univ. of Montana)
USDA = http://plants.usda.gov (US Dept of Agriculture)
FPNW = Flora of the Pacific Northwest (Hitchcock & Cronquist 1973)
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
206
Table 19. Non-native species found in riparian plant communities, both ungrazed and grazed sites, cont'd.
Brassicaceae Sisymbrium altisssimum L.
Tall tumblemustard
X
Brassicaceae Sisymbrium loeselii L.
Tumble Mustard
X
X
Brassicaceae Thlaspi arvense L.
Pennycress
X
X
Caryophyllaceae Lychnis alba P. Mill.
White Campion
N
X
Caryophyllaceae Silene noctiflora L.
Bladder Flower Plant
X
N
Caryophyllaceae Stellaria media (L.) Vill.
Chickweed
X
X
Chenopodiaceae Atriplex heterosperma Bunge
Saltbush
X
X
Chenopodiaceae Chenopodium album L. var. album
Lamb's Quarter; White goosefoot
X
N
Chenopodiaceae Chenopodium botrys L.
Jerusalem-Oak Goosefoot
X
X
Chenopodiaceae Chenopodium glaucum L.
Oakleaf Goosefoot
X
N
Chenopodiaceae Kochia scoparia (L.) Schrad.
Kochia; Summer Cypress
X
X
Chenopodiaceae Salsola kali L.
Russian Thistle
X
X
Chenopodiaceae Spinacia oleracea?? L.
Spinach
Convolvulaceae Convolvulus arvensis L.
Field Bindweed
X
X
Elaeagnaceae Elaeagnus angustifolia L.
Russian Olive
X
X
Euphorbiaceae Euphorbia esula L.
Leafy Spurge
X
X
Fabaceae Medicago lupulina L.
Black Medic; Hop Clover
X
X
Fabaceae Melilotus alba Medikus
White Sweet Clover
X
X
Fabaceae Melilotus officinalis (L.) Lam.
Yellow Sweet Clover
X
X
Fabaceae Trifolium fragiferum L.
Strawberry Clover
X
X
Fabaceae Trifolium hybridum L.
Alsike Clover
X
X
Fabaceae Trifolium pratense L.
Red Clover
X
X
Fabaceae Trifolium repens L.
White Clover
X
X
Fumariaceae Fumaria officianalis L.
Fumitory
X
X
Juncaceae Juncus compressus Jacq.
Roundfruit Rush
N
N
Lamiaceae Galeopsis tetrahit L.
Hemp Nettle
X
X
Lamiaceae Glechoma hederocea (?) L.
Ground Ivy
X
X
Lamiaceae Nepeta cataria L.
Catnip
X
X
Liliaceae Asparagus officinalis L.
Wild Asparagus
X
X
Poaceae Agropyron cristatum (L.) Gaertn.
Crested Wheatgrass
X
X
Poaceae Alopecurus arundinaceus Poir.
Garrison Creeping Foxtail
X
0
Poaceae Bromus inermis Leyss. ssp. inermis
Smooth Bromegrass
X
X
Poaceae Bromus japonicus Thunb. ex Murr.
Japanese Bromegrass
X
X
207
Table 19. Non-native species found in riparian plant communities, both ungrazed and grazed sites, cont'd.
Poaceae Bromus mollis aunct. non L.
Soft brome
X
X
X
Poaceae Bromus tectorum L.
Cheatgrass
X
X
X
Poaceae Crypsis alopecuroides (Piller & Mitterp.) Schrad.
Lovegrass
X
0
X
Poaceae Dactylis glomerata L.
Orchard Grass
X
X
X
Poaceae Echinochloa crus-galli (L.) Beauv.
Barnyard Grass
X
N
X
Poaceae Elymus hispidus (Opiz) Melderis
Intermediate Wheatgrass
X
X
X
Poaceae Elymus repens (L.) Gould
Quackgrass
X
X
X
Poaceae Festuca arundinacea Schreb.
Tall Fescue
X
X
X
Poaceae Festuca pratensis Huds.
Meadow Fescue
X
X
X
Poaceae Phalaris arundinacea L.
Reed Canary Grass
X
X
N
Poaceae Phleum pratense L.
Timothy
X
X
X
Poaceae Poa compressa L
Canada Bluegrass
X
N
X
Poaceae Poa pratensis L.
Kentucky Bluegrass
X
X
N
Poaceae Poa sp. (probably pratensis)
Bluegrass
X
X
X
Poaceae Setaria glauca (L.) Beauv.
Yellow Bristlegrass or Foxtail
X
X
X
Poaceae Setaria viridis (L.) Beauv.
Green Bristlegrass or Foxtail
X
X
X
Polygonaceae Polygonum aviculare L.
Prostrate knotweed
N
N
X
Polygonaceae Polygonum convulvulus L.
Black Bindweed
X
X
X
Polygonaceae Rumex crispus L.
Curly Dock
X
X
X
Polygonaceae Rumex patientia L.
Patience Dock
X
Polygonaceae Rumex stenophyllus Ledeb.
Narrowleaf Dock
N
0
X
Scrophulariaceae Linaria dalmatica (L.) P. Mill.
Dalmation Toad Flax
X
X
X
Scrophulariaceae Verbascum thapsus L.
Mullein
X
X
X
Solanaceae Hyoscyamus niger L.
Henbane
X
X
X
Solanaceae Solanum dulcamara L.
Climbing Nightshade
X
X
X
Tamaricaceae Tamarix chinensis Lour.
Salt Cedar; Tamarisk
X
X
X
Ulmaceae Ulmus pumila L.
Siberian Elm
X
X
X
Caprifoliaceae Lonicera sp.
Honeysuckle
N
N both
208
Table 20. Number of plant communities in which each species occurs,
segregated by native/non-native. Ungrazed sites only.
Native Shrubs
Amelanchier alnifolia
Artemisia cana
Artemisia dracunculus
Artemisia frigida
Clematis ligusticifolia
Cornus stolonifera
Humulus lupulus
Juniperus scopulorum
Parthenocissus inserta
Prunus virginiana
Rhus trilobata
Ribes aureum
Ribes hudsonianum
Ribes setosum
Ribes sp.
Rosa sayi/R. woodsii
Salix amygdaloides
Salix exigua
Salix sp. (small leaved willow)
Shepherdia argentea
Symphoricarpos occidentalis
Toxicodendron rydbergii
Vitis riparia
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
Non-Native Shrubs
Artemisia absinthium
Elaeagnus angustifolia
Tamarix chinensis
X
X
X
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Average
1
1
1
Plant Cmmts
1
1
Number of
1
1
P deltoides
Salix exigua
N/X
N
N
N
P angustifolia
Sandbar
Native Trees
Fraxinus pennsylvanica
Populus angustifolia
Populus deltoides
Gravel
Plant Life Form
Native/Exotic
Totals: 139 native, 68 non-native, 207 spp total. 33% non-native.
3
4
4
3.7
2
1
1
1
3
3
1
3
2
3
3
3
2
3
1
3
5
5
1
2
3
2
3
2.4
2
4
3
3.0
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
?
N
N
N
N
N
N
N
N
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
1
2
3
1
5
1
3
1
3
3
1
2
2
1
2
2
2
5
1
1
4
1
1
1
3
2
2
5
2
1
1
2
1
1
1
1
2
5
1
3
1
2
5
Average
Plant Cmmts
Number of
P deltoides
P angustifolia
Salix exigua
Sandbar
Gravel
Native Forbs
Achillea millefolium
Agrimonia striata
Amaranthus albus
Ambrosia psilostachya
Anemone sp.
Apocynum sibiricum
Arabis holboellii
Asclepias speciosa
Asclepias verticillata
Aster ascendens
Aster hesperius
Aster subspicatus
Cicuta douglasii
Cirsium undulatum
Conyza canadensis
Epilobium paniculatum
Equisetum arvense
Equisetum hyemale
Equisetum laevigatum
Equisetum pratense
Equisetum sylvaticum
Equisetum variegatum
Equisetum sp.
Erysimum asperum
Fragaria vesca
Galium aparine
Galium bifolium
Geum macrophyllum
Glycyrrhiza lepidota
Gnaphalium palustre
Helianthus annuus
Heterotheca villosa
Iris missouriensis
Iva xanthifolia
Lactuca pulchella
Lonicera sp.
Lycopus americanus
Lysimachia ciliata
Mentha arvensis
Mimulus guttatus
Oenethera villosa
Oxytropis deflexa
Parietaria pensylvanica
Plantago major
Native/Exotic
209
Table 20. Number of plant communities in which each species occurs, cont'd.
2.1
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
3
4
1
1
2
4
3
3
2
2
2
1
2
1
3
1
1
4
1
3
1
1
2
3
1
1
1
3
1
2
Average
Plant Cmmts
Number of
P deltoides
P angustifolia
Salix exigua
Sandbar
Gravel
Native Forbs, cont'd.
Polygonum achoreum
Polygonum amphibium
Polygonum douglasii
Polygonum lapathifolium
Polygonum sp.
Portulaca oleracea
Potentilla anserina
Potentilla gracilis
Potentilla norvegica
Potentilla paradoxa
Ranunculus cymbalaria
Ranunculus Macounii
Ranunculus sceleratus
Rorippa palustris v. hispida
Rudbeckia laciniata
Rumex salicifolius
Sagittaria cuneata
Smilacina stellata
Solanum rostratum
Solanum sarrachoides
Solidago gigantea
Solidago mollis
Solidago occidentalis
Stachys palustris
Thalictrum dasycarpum
Urtica dioica
Verbena bracteata
Verbena hastata
Veronica americana
Veronica anagallis-aquatica
Vicia americana
Viola sp.
Xanthium strumarium
Native/Exotic
210
Table 20. Number of plant communities in which each species occurs, cont'd.
211
Table 20. Number of plant communities in which each species occurs, cont'd.
Non-native Forbs
N/X G
S
SE PA PD # Cmts Avrg
Amaranthus blitoides
X
1
1
2.6
Amaranthus retroflexus
X
1
1
Arctium minus
X
1
1
1
1
4
Artemisia biennis
X
1
1
1
1
4
Asparagus officinalis
X
1
1
Asperugo procumbens
X
1
1
Brassica rapa
X
1
1
Centaurea maculosa
X
1
1
1
1
4
Chenopodium album
X
1
1
1
1
4
Chenopodium botrys
X
1
1
2
Chenopodium glaucum
X
1
1
Cirsium arvense
X
1
1
1
1
1
5
Cirsium vulgare
X
1
1
1
1
4
Conium maculatum
X
1
1
1
1
4
Convolvulus arvensis
X
1
1
Cynoglossum officinale
X
1
1
1
1
1
5
Descurainia sophia
X
1
1
2
Erysimum repandum
X
1
1
Euphorbia esula
X
1
1
1
1
1
5
Filago arvensis
X
1
1
2
Glechoma hederocea (?)
X
1
1
Kochia scoparia
X
1
1
Lactuca seriola
X
1
1
2
Lepidium campestre
X
1
1
Lepidium perfoliatum
X
1
1
2
Linaria dalmatica
X
1
1
Lychnis alba
X
1
1
Medicago lupulina
X
1
1
1
1
4
Melilotus alba
X
1
1
1
1
4
Melilotus officinalis
X
1
1
1
1
1
5
Melilotus sp.
X
1
1
2
Nepeta cataria
X
1
1
2
Polygonum aviculare
X
1
1
2
Polygonum convulvulus
X
1
1
2
Rumex crispus
X
1
1
1
3
Rumex stenophyllus
X
1
1
2
Salsola kali
X
1
1
2
Silene noctiflora
X
1
1
2
Sisymbrium altissimum
X
1
1
Sisymbrium loeselii
X
1
1
1
1
4
Solanum dulcamara
X
1
1
1
3
Sonchus uliginosus/S. asper
X
1
1
1
1
1
5
Tanacetum vulgare
X
1
1
1
1
1
5
Taraxacum officinale
X
1
1
1
1
1
5
Thlaspi arvense
X
1
1
2
Tragopogon dubius
X
1
1
1
3
Trifolium hybridum
X
1
1
2
Trifolium pratense
X
1
1
Trifolium repens
X
1
1
2
Verbascum thapsus
X
1
1
1
1
1
5
P deltoides
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
5
2
1
1
1
2
1
2
1
5
2
3
2
2
2
2
2
4
2
3
1
1
2
1
1
2
2
1
1
2
1
1
1
2
1
1
1
2
2
Average
P angustifolia
1
1
1
Plant Cmmts
Salix exigua
1
1
Number of
Sandbar
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
Gravel
Native Graminoids, cont'd.
Agrostis scabra
Agrostis stolonifera
Alopecurus aequalis
Calamovilfa longifolia
Carex aquatilis
Carex arthrostachya
Carex lanuginosa
Carex lenticularis
Carex microptera
Carex nebrascensis
Carex sp.
Deschampsia cespitosa
Eleocharis palustris
Elymus canadensis
Elymus cinereus
Elymus elymoides
Elymus lanceolatus
Elymus smithii
Elymus trachycaulus/E. sp.
Eragrostis hypnoides
Hordeum jubatum
Hordeum pusillum
Juncus articulatus
Juncus balticus
Juncus bufonius
Juncus ensifolius
Juncus interior
Juncus longistylis
Juncus nodosus
Juncus torreyi
Juncus sp.
Muhlenbergia racemosa
Panicum capillare
Poa juncifolia (?)
Poa palustris
Scirpus maritimus
Scirpus pungens
Scirpus validus
Spartina pectinata
Sporobolus cryptandrus
Native/Exotic
212
Table 20. Number of plant communities in which each species occurs, cont'd.
1.8
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
5
5
2
3
2
3
1
5
1
2
5
2
3
5
Average
1
Plant Cmmts
1
1
1
1
1
1
Number of
1
1
1
Salix exigua
Sandbar
1
1
1
1
1
1
1
P deltoides
1
1
P angustifolia
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Gravel
Non-Narive Graminoids
Agropyron cristatum
Alopecurus arundinaceus
Bromus inermis
Bromus japonicus
Bromus tectorum
Crypsis alopecuroides
Dactylis glomerata
Echinochloa crus-galli
Elymus repens
Festuca arundinacea
Juncus compressus
Phalaris arundinacea
Phleum pratense
Poa compressa
Poa pratensis
Native/Exotic
213
Table 20. Number of plant communities in which each species occurs, cont'd.
3.0
214
Table 21. Comparison of ungrazed and grazed gravelbar sites, cover data & t test results.
Species grouped by life form, then in order by cover.
AvCvr StDev
Separate Pooled
UNGRAZED SITES (n = 14)
Average cover of non-native species/ungr site 0.046 0.047
variance variance
Average cover of species/ungr site
0.158 0.087
0.470
0.540
0.911
0.924
Percent cover of non native species/ungr site 34% 35%
GRAZED SITES (n = 6)
Average cover of non-native species/grzdsite
Average cover of species/grzdsite
Percent cover of non native species/grzdsite
AvCvr StDev
0.048 0.040
0.134 0.026
37% 27%
UNGRAZED
Native/Non-native
TREES
Avrg cvr of non-ntv tree spp, ungr
Avrg cvr of non-ntv tree spp, grzd
Salicaceae Populus angustifolia
Salicaceae Populus deltoides
Avrg cover of tree species, ungr
Avrg cover of tree species, grzd
Avg
Sum
N/X Cvr
Cvr
0.000
0.000
N 0.032 0.446
N 0.003 0.042
0.035
0.033
SHRUBS
% Avrg cvr of non-ntv shrubs, ungr
% Avrg cvr of non-ntv shrubs, grzd
Avrg cvr of non-ntv shrubs ungr
Avrg cvr of non-ntv shrub spp, grzd
Tamaricaceae Tamarix chinensis
15%
2%
0.007
0.000
X 0.007
Salicaceae Salix exigua
Salicaceae Salix amygdaloides
Salicaceae Salix rigida
Avrg cvr native shrub species, ungr
Avrg cover of native shrub spp, grzd
Avrg cover of shrub species, ungr
Avrg cover of shrub species, grzd
N 0.047
N 0.011
N 0.000
0.058
0.025
0.064
0.025
Avrg % cvr of non-ntv forb spp, ungr
Avrg % cvr of non-ntv forb spp, grzd
Avrg cvr of non-ntv forb spp, ungr
Avrg cvr of non-ntv forb spp, grzd
Fabaceae Melilotus alba
Fabaceae Melilotus officinalis
Polygonaceae Rumex stenophyllus
Asteraceae Cirsium arvense
Polygonaceae Polygonum lapathifolium
Asteraceae Centaurea maculosa
Euphorbiaceae Euphorbia esula
Fabaceae Melilotus sp.
Asteraceae Taraxacum officinale
Chenopodiaceae Chenopodium album
56%
49%
0.020
0.022
X
X
X
X
X
X
X
X
X
X
0.011
0.003
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
GRAZED
Avg Sum
Cvr
Cvr
0.031
0.002
0.185
0.014
T test, ungr vs grzd
Separate Pooled
variance variance
0.964
0.837
0.970
0.857
0.939
0.950
0.16
0.165
0.35
0.356
0.092
0.000
0.001
0.654
0.151
0
0.022
0.002
0.000
0.132
0.338
0.504
0.014
0.333
0.521
0.001 Insufficient Data
0.130
0.155
0.045
0.017
0.007
0.007
0.006
0.006
0.006
0.005
0.004
0.001
0.001
0.000
0.001
0.000
0.000
0.006
0.000
0.001
0.001
0.005
0.004
0
0.003
0.002
0
0.037
0
0.006
0.004
0.286
0.855
0.890
0.184
0.377
0.186
0.377
Insufficient Data
1.000
1.000
0.713
0.742
I. D.
0.295
0.083
0.366
0.485
0.195
0.313
215
Table 21. Comparison of ungrazed and grazed gravelbar sites, cover data & t tests, cont'd.
T test, ungr vs grzd
UNGRAZED GRAZED
FORBS
AvCvr Ttl cvr AvCvr Ttl Cvr separate pooled
Asteraceae Tanasetum vulgare
X 0.000 0.003
0.002 0.014
0.140
0.020
X 0.000 0.003
0.002 0.009
0.315
0.101
Fabaceae Medicago lupulina
X 0.000 0.003
0.000
0
I. D.
Portulaceae Portulaca oleracea
Asteraceae Sonchus uliginosus/S. asp
X 0.000 0.002
0.001 0.006
0.432
0.202
X 0.000 0.002
0.001 0.005
0.346
0.157
Scrophulariaceae Verbascum thapsus
X 0.000 0.002
0.000
0
I. D.
Caryophyllaceae Silene noctiflora
Polygonaceae Rumex crispus
X 0.000 0.001
0.001 0.008
0.388
0.154
Chenopodiaceae Chenopodium botrys
X 0.000 0.001
0.001 0.007
0.226
0.046
X 0.000 0.001
0.000
0
I. D.
Apiaceae Conium maculatum
X 0.000 0.001
0.000
0
I. D.
Asteraceae Filago arvensis
X 0.000 0.001
0.000
0
I. D.
Brassicaceae Sisymbrium loeselii
0
I. D.
Polygonaceae Rumex sp.
0.000 0.001 0.000
X 0.000 0.001
0.000
0 Insufficient Data
Solanaceae Solanum dulcamara
Chenopodiaceae Chenopodium glaucum
X 0.000
0
0.003 0.018
I. D.
X 0.000
0
0.000 0.001
I. D.
Asteraceae Cirsium vulgare
X 0.000
0
0.000 0.001
I. D.
Asteraceae Tragopogon dubius
X 0.000
0
0.000 0.001
I. D.
Chenopodiaceae Salsola kali
Polygonaceae Rumex salicifolius
Plantiginaceae Plantago major
Brassicaceae Rorippa palustris
Lamiaceae Mentha arvensis
Onagraceae Oenethera villosa
Asteraceae Solidago gigantea
Verbenaceae Verbena bracteata
Amaranthaceae Amaranthus albus
Rubiaceae Galium bifolium
Scrophulariaceae Veronica americana
Rosaceae Potentilla norvegica
Asteraceae Aster ascendens
Rosaceae Potentilla paradoxa
Polygonaceae Polygonum aviculare
Ranunculaceae Ranunculus cymbalar
Ranunculaceae Ranunculus sceleratus
Equisetaceae Equisetum variegatum
Scrophulariaceae Veronica anagallis-aquatica
Alismataceae Sagittaria cuneata
Apocynaceae Apocynum sibiricum
Asteraceae Aster hesperius
Asteraceae Cirsium undulatum
Equisetaceae Equisetum laevigatum
Fabaceae Glycyrrhiza lepidota
Onagraceae Epilobium paniculatum
Polygonaceae Polygonum sp.
Asteraceae Conyza canadensis
Asteraceae Gnaphalium palustre
Polygonaceae Polygonum amphibium
Euphorbiaceae Euphorbia glyptosperma
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
0.004
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.051
0.012
0.012
0.009
0.007
0.005
0.005
0.004
0.003
0.003
0.002
0.002
0.002
0.002
0.002
0.002
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0
0
0
0
0.005
0.002
0.001
0.001
0.000
0.000
0.000
0.001
0.000
0.000
0.002
0.000
0.000
0.000
0.000
0.000
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.004
0.003
0.001
0.000
0.027
0.814
0.836
0.01
0.45
0.372
0.003
0.705
0.779
0.008
0.515
0.545
0.001
0 Insufficient Data
0
I. D.
0.004
0.522
0.491
0
I. D.
0
I. D.
0.009
0.348
0.123
0.001
0.905
0.898
0.001
0.915
0.924
0
I. D.
0
I. D.
0
I. D.
0.003
0.117
0.028
0.003
I. D.
0
I. D.
0
I. D.
0
I. D.
0
I. D.
0
I. D.
0
I. D.
0
I. D.
0
I. D.
0.022
I. D.
0.017
I. D.
0.004
I. D.
0.002
I. D.
216
Table 21. Comparison of ungrazed and grazed gravelbar sites, cover data & t tests, cont'd.
T test, ungr vs grzd
UNGRAZED GRAZED
FORBS, cont'd.
AvCvr Ttl cvr AvCvr Ttl Cvr separate pooled
Asteraceae Achillea millefolium
N 0.000
0
0.000 0.001
I. D.
Brassicaceae Thelopodium integrifolium
N 0.000
0
0.000 0.001
I. D.
N 0.000
0
0.000 0.001
I. D.
Polygonaceae Polygonum achoreum
N 0.000
0
0.000 0.001
I. D.
Scrophulariaceae Veronica peregrina
N 0.000
0
0.000 0.001
I. D.
Solanaceae Solanum triflorum
0.010
Avrg cvr of native forb species, ungr
Avrg cvr of native forb species, grzd
0.020
Avrg cover of forb species, ungr
0.029
Avrg cover of forb species, grzd
0.042
0.450
0.485
GRAMINOIDS
Avrg % cvr of non-ntv gramnd spp ungr
Avg % cvr of non-ntv gramnd spp, grzd
Avrg cvr of non-ntv graminoid spp, ungr
Avrg cvr of non-ntv graminoid spp, grzd
Poaceae Elymus repens
Poaceae Alopecurus arundinaceus
Poaceae Phalaris arundinacea
Poaceae Poa pratensis
Poaceae Poa compressa
Poaceae Bromus inermis
Poaceae Bromus tectorum
Poaceae Phleum pratense
Poaceae Crypsis alopecuroides
Poaceae Echinochloa crus-galli
Poaceae Setaria viridis
Poaceae Deschampsia cespitosa
Poaceae Agrostis stolonifera
Poaceae Poa palustris
Poaceae Hordeum jubatum
Cyperaceae Carex sp.
Cyperaceae Eleocharis palustris
Poaceae Elymus trachycaulus/A. sp.
Poaceae Alopecurus aequalis
Poaceae Elymus elynoides
Juncaceae Juncus interior
Juncaceae Juncus sp.
Poaceae Elymus smithii
Poaceae Panicum capillare
Cyperaceae Carex arthrostachya
Juncaceae Juncus longistylis
Juncaceae Juncus tenuis
Juncaceae Juncus torreyi
Poaceae Sporobolus cryptandrus
Avrg cover of native gramnd spp, ungr
Avrg cover of native grmnd spp, grzd
Avrg cover of graminoid species, ungr
Avrg cover of graminoid species, grzd
44%
54%
0.020
0.025
X
X
X
X
X
X
X
X
X
X
X
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
0.010
0.009
0.030
0.035
0.792
0.008
0.005
0.005
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.113
0.067
0.063
0.017
0.007
0.003
0.002
0.002
0.001
0
0
0.022
0.000
0.000
0.002
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.131
0.538
0 calculator
0 calculator
0.011
0.675
0.007
0.537
0
I. D.
0
I. D.
0
I. D.
0
I. D.
0.001
I. D.
0.001
I. D.
0.006
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.087
0.014
0.013
0.009
0.007
0.003
0.002
0.002
0.002
0.001
0.001
0.001
0
0
0
0
0
0
0.001
0.003
0.001
0.000
0.000
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.008
0.015
0.007
0.002
0.001
0.004
0.006
0.003
0
0.001
0
0
0.002
0.001
0.001
0.001
0.001
0.001
0.733
0.363
0.364
0.184
0.584
0.385
0.396
0.585
0.828
0.465
0.571
0.439
0.785
0.594
0.245
0.344
0.512
I. D.
0.616
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
0.117
0.127
0.320
0.855
0.844
0.541
217
Table 22. Comparison of ungrazed and grazed sandbar sites, cover data & t test results.
Species grouped by life form, then in order by cover.
AvCvr StDev T tests,
0.155 0.24 grazed vs.
0.386 0.25 ungrazed
37% 31%
Ungrazed Sites (n = 8)
Average cover of non-ntv spp/site
Average cover of spp/site
% cover of non ntv spp/site
Grazed Sites (n = 4)
Average cover of non-ntv spp/site
Average cover of spp/site
% cover of non ntv spp/site
Sep Var Pool Var
0.21
0.361
0.105
0.167
0.519
0.555
AvCvr StDev
0.037 0.022
0.186 0.141
26% 24%
UNGRAZED GRAZED
T test, ungr v. grzd
Avg Sum
Avrg Sum Separate Pooled
Cover Cover Cover Cover variance variance
Native/Non-native
TREES
N/X
Cover of non-ntv tree spp, Ungr
0
Cover of non-ntv tree spp, Grzd
0
Salicaceae Populus deltoides
N 0.002 0.017
Salicaceae Populus angustifolia
N 0.001 0.005
Total cover of tree spp, Ungr
0.003
Total cover of tree spp, Grzd
0.012
SHRUBS
% cover of non-ntv shrub spp, Ungr 28%
% cover of non-ntv shrub spp, Grzd
0%
Cover of non-ntv shrub spp, Ungr
0.008
Cover of non-ntv shrub spp, Grzd
0.000
Tamaricaceae Tamarix chinensis
X 0.008 0.061
Salicaceae Salix exigua
Salicaceae Salix amygdaloides
Cover of ntv shrub spp, Ungr
Cover of ntv shrub spp, Grzd
Total cover of shrub spp, Ungr
Total cover of shrub spp, Grzd
N 0.090 0.720
N 0.002 0.016
0.092
0.003
0.100
0.003
0.007 0.029
0.004 0.017
0.000 0.000
0.003 0.010
0.001 0.002
FORBS
% cover of non-ntv forb spp, Ungr
% cover of non-ntv forb spp, Grzd
Cover of non-ntv forb spp, Ungr
Cover of non-ntv forb spp, Grzd
38%
41%
0.065
0.025
Chenopodiaceae Chenopodium glaucum
X
Chenopodiaceae Chenopodium album
X
Polygonaceae Rumex stenophyllus
X
Brassicaceae Thlaspi arvense
X
Chenopodiaceae Kochia scoparia
X
Polygonaceae Rumex sp.
Polygonaceae Polygonum aviculare
X
Asteraceae Taraxacum officinale
X
Brassicaceae Lepidium perfoliatum
X
Fabaceae Melilotus officinalis
X
Asteraceae Cirsium arvense
X
0.043
0.006
0.004
0.002
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.342
0.046
0.028
0.019
0.010
0.009
0.009
0.008
0.007
0.006
0.004
0.007
0.001
0.000
0.000
0.000
0.000
0.000
0.001
0.000
0.000
0.000
0.028
0.002
0.000
0.000
0.001
0.000
0.000
0.002
0.000
0.001
0.000
0.323
0.458
0.141
0.253
Insufficient Data
0.079
0.187
0.084
0.429
0.195
0.567
0.060
0.154
0.244
0.416
0.231
I. D.
I. D.
0.297
I. D.
I. D.
0.381
I. D.
0.474
I. D.
0.395
0.562
0.386
0.445
0.49
0.596
218
Table 22. Comparison of ungrazed and grazed sandbar sites, cover data & t test results.
T test, ungr v. grzd.
UNGRAZED GRAZED
Avg Sum
Avrg Sum Separate Pooled
FORBS, cont'd.
N/X Cover Cover Cover Cover variance variance
Asteraceae Lactuca seriola
X 0.001 0.004 0.000 0.000 I. D.
Chenopodiaceae Chenopodium botrys
X 0.001 0.004 0.000 0.000 I. D.
Fabaceae Medicago lupulina
X 0.001 0.004 0.001 0.003
0.593
0.672
Asteraceae Sonchus uliginosus/S. asper
X 0.000 0.003 0.000 0.000 I. D.
Brassicaceae Sisymbrium loeselii
X 0.000 0.003 0.000 0.000 I. D.
Asteraceae Filago arvensis
X 0.000 0.002 0.000 0.000 I. D.
Asteraceae Tanacetum vulgare
X 0.000 0.002 0.000 0.001
1.000
1.000
Boraginaceae Asperugo procumbens
X 0.000 0.001 0.000 0.000 I. D.
Brassicaceae Erysimum repandum
X 0.000 0.001 0.000 0.000 I. D.
Brassicaceae Sisymbrium altissimum
X 0.000 0.001 0.000 0.000 I. D.
Amaranthaceae Amaranthus blitoides
X 0.000 0.002 0.000 0.000 I. D.
Asteraceae Artemisia biennis
X 0.000 0.002 0.000 0.000 I. D.
Polygonaceae Rumex crispus
X 0.000 0.001 0.000 0.000 I. D.
Scrophulariaceae Verbascum thapsus
X 0.000 0.001 0.000 0.000 I. D.
Euphorbiaceae Euphorbia esula
X 0.000 0.000 0.014 0.054 I. D.
Polygonaceae Polygonum lapathifolium
Polygonaceae Polygonum amphibium
Equisetaceae Equisetum arvense
Asteraceae Xanthium strumarium
Verbenaceae Verbena bracteata
Equisetaceae Equisetum laevigatum
Asteraceae Solidago occidentalis
Asteraceae Aster hesperius
Rubiaceae Galium bifolium
Asteraceae Iva xanthifolia
Rosaceae Potentilla paradoxa
Polygonaceae Polygonum douglasii
Fabaceae Glycyrrhiza lepidota
Brassicaceae Rorippa palustris v. hispida
Ranunculaceae Ranunculus cymbalaria
Asteraceae Gnaphalium palustre
Solanaceae Solanum rostratum
Polygonaceae Polygonum achoreum
Onagraceae Epilobium paniculatum
Scrophulariaceae Veronica americana
Amaranthaceae Amaranthus albus
Equisetaceae Equisetum variegatum
Onagraceae Oenethera villosa
Asteraceae Helianthus annuus
Lamiaceae Mentha arvensis
Rosaceae Potentilla norvegica
Apiaceae Cicuta douglasii
Ranunculaceae Ranunculus sceleratus
Plantiginaceae Plantago major
Scrophulariaceae Veronica anagallis-aquatica
Iridaceae Iris missouriensis
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
0.033
0.009
0.008
0.006
0.006
0.006
0.005
0.005
0.004
0.003
0.002
0.002
0.002
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.261
0.068
0.060
0.051
0.049
0.045
0.040
0.039
0.034
0.021
0.018
0.016
0.012
0.009
0.007
0.007
0.006
0.005
0.005
0.004
0.003
0.002
0.002
0.002
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.002
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.001
0.000
0.000
0.001
0.005
0.005
0.000
0.001
0.000
0.000
0.000
0.051
0.001
0.000
0.002
0.000
0.000
0.000
0.017
0.004
0.000
0.006
0.000
0.000
0.000
0.001
0.000
0.000
0.000
0.000
0.000
0.005
0.000
0.000
0.005
0.020
0.019
0.000
0.003
0.000
0.000
0.000
0.203
0.003
0.000
0.008
0.001
0.000
0.000
0.066
0.015
0.001
0.185
I. D.
I. D.
I. D.
0.359
I. D.
I. D.
I. D.
I. D.
I. D.
0.658
I. D.
I. D.
I. D.
I. D.
0.475
I. D.
0.894
I. D.
I. D.
I. D.
0.388
0.383
I. D.
0.347
0.675
I. D.
0.471
I. D.
I. D.
I. D.
0.334
0.514
0.74
0.264
0.890
0.164
0.239
0.132
0.624
0.258
219
Table 22. Comparison of ungrazed and grazed sandbar sites, cover data & t test results.
UNGRAZED GRAZED
T test, ungr v. grzd.
Avg Sum
Avrg Sum Separate Pooled
FORBS, cont'd.
Cover Cover Cover Cover variance variance
Scrophulariaceae Veronica peregrina
N 0.000 0.000 0.000 0.001 I. D.
Scrophulariaceae Veronica scutellata
N 0.000 0.000 0.000 0.001 I. D.
Cover of ntv forb spp, Ungr
0.096
Cover of ntv forb spp, Grzd
0.090
Total cover of forb spp, Ungr
0.161
Total cover of forb spp, Grzd
0.113
0.551
0.630
GRAMINOIDS
% cover non-ntv gramnd spp, Ungr
41%
% cover non-ntv gramnd spp, Grzd
13%
Cover of non-ntv gramnd spp, Ungr 0.052
Cover of non-ntv gramnd spp, Grzd 0.012
Poaceae Echinochloa crus-galli
X 0.039 0.310
Poaceae Elymus repens
X 0.007 0.052
Poaceae Bromus tectorum
X 0.003 0.023
Poaceae Bromus japonicus
X 0.001 0.011
Poaceae Phalaris arundinacea
X 0.001 0.011
Poaceae Bromus inermis
X 0.001 0.005
Poaceae Crypsis alopecuroides
X 0.000 0.002
Poaceae Poa sp.
X 0.000 0.000
Juncaceae Juncus compressus
X 0.000 0.001
Poaceae Poa pratensis
X 0.000 0.000
Cyperaceae Eleocharis palustris
Cyperaceae Carex nebrascensis
Cyperaceae Carex lanuginosa
Cyperaceae Scirpus maritimus
Poaceae Eragrostis hypnoides
Juncaceae Juncus longistylis
Juncaceae Juncus ensifolius
Poaceae Agrostis stolonifera
Poaceae Alopecurus aequalis
Poaceae Hordeum jubatum
Poaceae Agrostis scabra
Poaceae Sporobolus cryptandrus
Cyperaceae Carex sp.
Juncaceae Juncus bufonius
Juncaceae Juncus articulatus
Poaceae Poa juncifolia (?)
Juncaceae Juncus tenuis
Poaceae Panicum capillare
Juncaceae Juncus torreyi
Cyperaceae Cyperus aristatus
Poaceae Elymus trachycaulus/A. sp.
Cover of ntv gramnd spp, Ungr
Cover of ntv gramnd spp, Grzd
Total cover of gramnd spp, Ungr
Total cover of gramnd spp, Grzd
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
0.070
0.047
0.122
0.059
0.030
0.025
0.006
0.003
0.002
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.241
0.200
0.044
0.024
0.012
0.011
0.007
0.006
0.005
0.003
0.003
0.003
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.012
0.000
0.000
0.000
0.001
0.001
0.000
0.000
0.000
0.000
0.046
0.000
0.001
0.273
I. D.
0.258
0.323
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
0.021
0.000
0.000
0.000
0.000
0.000
0.000
0.006
0.001
0.003
0.000
0.000
0.000
0.000
0.000
0.000
0.010
0.004
0.001
0.000
0.000
0.084
0.000
0.000
0.000
0.001
0.001
0.000
0.023
0.004
0.013
0.000
0.000
0.001
0.001
0.000
0.000
0.038
0.016
0.002
0.001
0.001
0.679
I. D.
I. D.
I. D.
0.437
0.446
I. D.
0.450
0.762
0.443
I. D.
I. D.
0.675
0.675
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
0.215
0.416
0.416
0.479
0.722
0.579
0.586
0.241
0.746
0.230
0.624
0.624
0.307
220
Table 23. Comparison of ungrazed vs. grazed Salix exigua sites, cover data & t test results
Species grouped by life form, then in order by cover.
UNGRAZED SITES (n = 22)
Avrg cover of non-ntv spp/ungrazed site
Avrg cover of spp/ungrazed site
non-ntv spp cover/total cover, ungr sites
AvCvr StDev
0.394 0.243
1.144 0.309
34% 20%
GRAZED SITES (n = 10)
Avrg cover of non-ntv spp/grazed site
Avrg cover of spp/grazed site
non-ntv spp cover/total cover, grzd sites
AvCvr StDev
0.203 0.173
0.885 0.340
25% 20%
Native/non-native
TREES
N/X
Avrg cover of non-ntv tree spp, ungr
0
Avrg cover of non-ntv tree spp, grzd
0
Populus deltoides
N
Populus angustifolia
N
Fraxinus pennsylvanica
N
0.017
Avrg cover of all tree spp, ungr
Avrg cover of all tree spp, grzd
0.024
SHRUBS
Non-ntv shrub cvr/total shrub cvr, un
Non-ntv shrub cvr/total shrub cvr, gr
Avrg cover of non-ntv shrub spp, un
Avrg cover of non-ntv shrub spp, gr
Elaeagnus angustifolia
Tamarix chinensis
Artemisia absinthium
Salix exigua
Salix amygdaloides
Cornus stolonifera
Ribes hudsonianum
Symphoricarpos occidentalis
Ribes aureum
Rosa woodsii/R. sayi
Prunus virginiana
Ribes sp.
Salix sp. (small leaved willow)
Clematis ligusticifolia
Humulus lupulus
Ribes setosum
Vitis riparia
Rhus trilobata
Toxicodendron rydbergii
Juniperus scopulorum
Amelanchier alnifolia
Artemisia frigida
SepVar PoolVar
0.013 0.026
0.056 0.041
0.198 0.190
UNGRAZED
Avrg Total
Cover Cover
GRAZED
Avrg Total
Cover Cover
0.007 0.153
0.010 0.213
0.000 0.002
N/A
N/A
0.003 0.031
0.495
0.62
0.021 0.212
0.344 0.141
0.000 0.002
0.628 0.569
T test ungr v grzd
separate Pooled
variance variance
0.749
0.718
2%
1%
0.015
X 0.012 0.263
X 0.003 0.058
X 0.000 0.005
0.000 0.004
0.006 0.056
0.000 0.001
Insufficient Data
0.198 0.381
0.634 0.567
0.612 0.716
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
0.311
0.013
0.001
0.000
0.031
0.000
0.064
0.002
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.0005 0.0016
0.083 0.188
0.063 0.198
I. D.
0.427 0.355
I. D.
0.356 0.169
0.578 0.691
I. D.
I. D.
I. D.
I. D.
I. D.
0.340 0.485
I. D.
I. D.
I. D.
I. D.
I. D.
0.006
0.506
0.055
0.016
0.011
0.011
0.010
0.009
0.005
0.003
0.002
0.002
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
11.141
1.217
0.359
0.241
0.239
0.210
0.203
0.118
0.060
0.042
0.033
0.020
0.008
0.007
0.001
0.001
0.001
0.001
0.000
3.113
0.131
0.012
0.000
0.310
0.000
0.638
0.022
0.000
0.000
0.000
0.000
0.000
0.001
0.000
0.000
0.000
0.000
0.002
221
Table 23. Comparison of ungrazed vs grazed Salix exigua sites, cover & t tests, cont'd.
UNGRAZED GRAZED
T test ungr v grzd
Avrg Total
Avrg Total separate Pooled
SHRUBS, cont'd.
N/X Cover Cover Cover Cover variance variance
Avrg cover af all native shrub spp, ungr 0.632
0.423
Avrg cover of all native shrub spp, gr
Avrg cover of all shrub spp, ungr
0.647
Avrg cover of all shrub spp, grzd
0.429
0.041 0.030
FORBS
Non-ntv forb cvr/total forb cvr, ungr
Non-ntv forb cvr/total forb cvr, grzd
Avrg cover of non-ntv forb spp, ungr
Avrg cover of non-ntv forb spp, grzd
Cirsium arvense
Melilotus officinalis/M. alba
Solanum dulcamara
Cynoglossum officinale
Trifolium hybridum
Tanacetum vulgare
Sonchus uliginosus/S. asper
Taraxacum officinale
Verbascum thapsus
Arctium minus
Cirsium vulgare
Euphorbia esula
Sisymbrium loeselii
Conium maculatum
Tragopogon dubius
Silene noctiflora
Nepeta cataria
Medicago lupulina
Lactuca seriola
Descurainia sophia
Lepidium perfoliatum
Lychnis alba
Rumex crispus
Centaurea maculosa
Chenopodium album
Amaranthus retroflexus
Trifolium repens
Glycyrrhiza lepidota
Solidago gigantea
Solidago occidentalis
Equisetum hyemale var. affine
Smilacina stellata
Apocynum sibiricum
Lysimachia ciliata
Polygonum amphibium
70%
56%
0.133
0.091
0.241
0.357
0.216
0.257
0.92
I. D.
0.807
0.686
0.573
0.773
0.889
0.123
I. D.
0.98
I. D.
0.272
0.557
I. D.
0.33
0.361
I. D.
I. D.
I. D.
I. D.
0.628
I. D.
I. D.
I. D.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
0.073
0.025
0.012
0.010
0.002
0.002
0.002
0.002
0.002
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
1.600
0.560
0.262
0.212
0.054
0.037
0.036
0.034
0.033
0.026
0.019
0.010
0.009
0.008
0.006
0.006
0.005
0.003
0.002
0.001
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.043
0.003
0.000
0.009
0.000
0.001
0.001
0.002
0.002
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.011
0.003
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.015
0.425
0.030
0.001
0.086
0.000
0.013
0.011
0.024
0.021
0.010
0.001
0.000
0.004
0.000
0.001
0.001
0.000
0.106
0.025
0.000
0.000
0.000
0.000
0.001
0.001
0.001
0.150
N
N
N
N
N
N
N
N
0.007
0.006
0.005
0.004
0.003
0.003
0.002
0.002
0.162
0.125
0.116
0.088
0.068
0.067
0.036
0.036
0.017
0.017
0.009
0.000
0.000
0.000
0.000
0.002
0.166
0.27
0.168
0.425
0.087
0.725
0.001
0.341
0.000 I. D.
0.000 I. D.
0.000 I. D.
0.022
0.821
0.368
0.474
0.400
0.442
0.942
0.858
0.731
0.49
0.775
0.91
0.285
0.984
0.365
0.679
0.13
0.156
0.569
0.215
0.279
0.678
0.52
0.794
222
Table 23. Comparison of ungrazed vs grazed Salix exigua sites, cover & t tests, cont'd.
T test ungr v grzd
UNGRAZED GRAZED
Avrg Total
Avrg Total separate Pooled
FORBS, cont'd.
N/X Cover Cover Cover Cover variance variance
Ambrosia psilostachya
N 0.001 0.018 0.000 0.000 I. D.
Mentha arvensis
N 0.001 0.016 0.001 0.009
0.803 0.811
Aster ascendens
N 0.001 0.016 0.003 0.027
0.413 0.286
Equisetum arvense
N 0.001 0.014 0.026 0.261
0.353 0.149
Aster subspicatus
N 0.001 0.013 0.000 0.000 I. D.
Plantago major
N 0.000 0.010 0.005 0.053
0.305 0.115
Asclepias speciosa
N 0.000 0.010 0.000 0.001
0.454 0.608
Verbena bracteata
N 0.000 0.010 0.000 0.002
0.596 0.713
Equisetum variegatum
N 0.000 0.008 0.000 0.002
0.676 0.769
Oenethera villosa (=O.strigosa)
N 0.000 0.006 0.000 0.001
0.445 0.576
Conyza canadensis
N 0.000 0.006 0.029 0.291
0.346 0.143
Equisetum laevigatum
N 0.000 0.005 0.001 0.008
0.363 0.177
Heterotheca villosa
N 0.000 0.004 0.000 0.000 I. D.
Geum macrophyllum
N 0.000 0.003 0.000 0.000 I. D.
Verbena hastata
N 0.000 0.003 0.000 0.001
0.799 0.825
Equisetum sylvaticum
N 0.000 0.002 0.000 0.000 I. D.
Polygonum sp.
0.000 0.002 0.000 0.000 I. D.
Potentilla gracilis
N 0.000 0.002 0.000 0.000 I. D.
Potentilla paradoxa
N 0.000 0.002 0.000 0.000 I. D.
Galium aparine
N 0.000 0.002 0.000 0.000 I. D.
Xanthium strumarium
N 0.000 0.002 0.002 0.023
0.362 0.157
Cicuta douglasii
N 0.000 0.001 0.000 0.000 I. D.
Iris missouriensis
N 0.000 0.001 0.000 0.000 I. D.
Thalictrum dasycarpum
N 0.000 0.001 0.000 0.000 I. D.
Potentilla anserina
N 0.000 0.001 0.000 0.000 I. D.
Parietaria pensylvanica
N 0.000 0.001 0.000 0.000 I. D.
Polygonum lapathifolium
N 0.000 0.001 0.000 0.000 I. D.
Aster hesperius
N 0.000 0.001 0.000 0.001
0.628 0.569
Achillea millefolium
N 0.000 0.000 0.000 0.001 I. D.
Marsilea vestita
N 0.000 0.000 0.000 0.001 I. D.
Rumex salicifolius
N 0.000 0.000 0.000 0.001 I. D.
Typha latifolia
N 0.000 0.000 0.000 0.001 I. D.
Chenopodium fremontii
N 0.000 0.000 0.000 0.002 I. D.
Artemisia campestris
N 0.000 0.000 0.000 0.004 I. D.
Rudbeckia laciniata
N 0.000 0.000 0.001 0.005 I. D.
Avrg cover of all ntv forb spp, ungr
0.039
Avrg cover of all native forb spp, grzd 0.114
Avrg cover of all forb spp, ungr
0.172
Avrg cover of all forb spp, grzd
0.205
0.609 0.578
223
Table 23. Comparison of ungrazed vs grazed Salix exigua sites, cover & t tests, cont'd.
UNGRAZED GRAZED
T test ungr v grzd
Avrg Total
Avrg Total separate Pooled
GRAMINOIDS
N/X Cover Cover Cover Cover variance variance
Non-ntv grmnd cvr/total grmnd cvr, un 73%
Non-ntv grmnd cvr/total grmnd cvr, gr
41%
Avrg cover of non-ntv grmnd spp, un
0.246
Avrg cover of non-ntv grmnd spp, gr
0.108
0.070 0.061
Poa pratensis
X 0.025 0.544 0.064 0.644
0.487 0.301
Phalaris arundinacea
X 0.200 4.395 0.003 0.034
0.000 0.009
Elymus repens
X 0.017 0.368 0.039 0.394
0.299 0.162
Bromus inermis
X 0.003 0.055 0.000 0.003
0.212 0.395
Alopecurus arundinaceus
X 0.001 0.022 0.000 0.000 I. D.
Phleum pratense
X 0.001 0.011 0.000 0.002
0.551 0.668
Dactylis glomerata
X 0.000 0.010 0.000 0.000 I. D.
Bromus tectorum
X 0.000 0.007 0.000 0.004
0.843 0.859
Bromus japonicus
X 0.000 0.000 0.000 0.001 I. D.
Agrostis stolonifera
N
Poa palustris
N
Carex sp.
N
Carex aquatilis
N
Spartina pectinata
N
Elymus lanceolatus
N
Elymus trachycaulus/A. sp.
N
Deschampsia cespitosa
N
Carex lanuginosa
N
Elymus elymoides
N
Carex microptera
N
Juncus nodosus
N
Sporobolus cryptandrus
N
Eleocharis palustris
N
Hordeum jubatum
N
Carex lenticularis
N
Juncus sp.
N
Juncus longistylis
N
Calamagrostis stricta
N
Carex athrostachya
N
Carex brevior
N
Scirpus pungens
N
Panicum capilare
N
Carex nebrascensis
N
Juncus balticus
N
Elymus canadensis
N
Agrostis scabra
N
Avrg cover of native grmnd spp, ungr 0.063
Avrg cover of native grmnd spp, grzd 0.118
Avrg cover of graminoid spp, ungr
0.309
Avrg cover of graminoid spp, grzd
0.226
0.019
0.014
0.010
0.007
0.004
0.002
0.002
0.002
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.410
0.299
0.220
0.162
0.088
0.054
0.053
0.040
0.022
0.013
0.007
0.002
0.002
0.002
0.002
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.039
0.006
0.022
0.000
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.001
0.001
0.006
0.040
0.389
0.059
0.215
0.000
0.008
0.000
0.004
0.002
0.000
0.000
0.003
0.000
0.000
0.006
0.007
0.002
0.000
0.001
0.001
0.002
0.002
0.002
0.002
0.008
0.010
0.058
0.400
0.596
0.404
0.472
I. D.
0.441
I. D.
0.32
0.386
I. D.
I. D.
0.965
I. D.
I. D.
0.239
0.161
I. D.
I. D.
0.628
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
0.341
0.422
0.552
0.464
0.598
0.498
0.557
0.968
0.079
0.036
0.569
0.307
224
Table 24. Comparison of ungrazed and grazed Populus angustifolia sites, cover data
and t test results. Species grouped by life form, then in order by cover.
UNGRAZED SITES (n = 8) (0% cow pie)
Avrg cvr of non-ntv spp
Avrg cvr of species
Cover non-natives/total cover
AvCvr StDev
0.228 0.170
1.680 0.258
14% 10%
GRAZED SITES (n = 13) (3.5% cow pie)
Avrg cvr of non-ntv spp
Avrg cvr of species
Cover non-natives/total cover
T tests,
grazed vs.
ungrazed
SepVar PoolVar
0.054 0.076
0.098 0.082
0.026 0.039
AvCvr StDev
0.416 0.249
1.483 0.226
27% 14%
TREES
Avrg cvr of non-ntv tree spp, ungr
Avrg cvr of non-ntv tree spp, gr
Populus angustifolia
Fraxinus pennsylvanica
Avrg cvr of tree species, ungr
Avrg cvr of tree species, gr
UNGRAZED
Avrg Total
N/X Cover Cover
0
0
N 0.865 6.920
N 0.015 0.120
0.880
0.858
SHRUBS
Avrg cvr of non-ntv shrub spp, ung
Avrg cvr of non-ntv shrub spp, gr
Symphoricarpos occidentalis
Cornus stolonifera
Juniperus scopulorum
Rosa sayi/R. woodsii
Rhus trilobata
Shepherdia argentea
Salix amygdaloides
Ribes aureum
Ribes setosum
Ribes hudsonianum
Prunus virginiana
Salix exigua
Artemisia frigida
Clematis ligusticifolia
Betula occidentalis
Avrg cvr of shrub species, ungr
Avrg cvr of shrub species, grzd
0
0
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
0.467
0.078
FORBS
Cvr non-ntv forbs/cover forbs, ungr
Cvr non-ntv forbs/cover forbs, grzd
Avrg cvr of non-ntv forb spp, ungr
Avrg cvr of non-ntv forb spp, grzd
Cirsium arvense
Arctium minus
Tanacetum vulgare
46%
55%
0.063
0.101
X 0.040 0.318
X 0.013 0.102
X 0.009 0.070
Native/non-native
0.151
0.102
0.096
0.049
0.019
0.017
0.015
0.014
0.005
0
0
0
0
0
0
1.208
0.815
0.767
0.395
0.148
0.133
0.120
0.108
0.039
0.001
0.001
0.000
0.000
0.000
0.000
GRAZED
Avrg Total
Cover Cover
0.858 11.16
0.000 0.000
T test ungr v grzd
Separate
N/A
N/A
0.902 0.893
Insufficient Data
0.693
0.025
0.000
0.025
0.009
0.004
0.006
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.009
0.319
0.001
0.326
0.115
0.052
0.075
0.000
0.002
0.001
0.000
0.003
0.004
0.001
0.001
0.112
Pooled
variance variance
0.663
N/A
N/A
0.200 0.086
0.058 0.008
0.299 0.186
0.173 0.074
0.277 0.181
0.545 0.445
Insufficient Data
0.336 0.197
0.143 0.046
I.D.
0.617 0.657
Insufficient Data
I.D.
I.D.
I.D.
0.0045 0.0001
0.004 0.058
0.001 0.098
0.000 0.001
0.435
0.025
I.D.
0.355
0.494
0.003
0.214
225
Table 24. Comparison of ungrazed and grazed Populus angustifolia sites, cont'd.
T test ungr v grzd
UNGRAZED
GRAZED
FORBS, cont'd.
Avrg Total
Avrg Total
Separate Pooled
Cover Cover Cover Cover
variance variance
Taraxacum officinale
X 0.001 0.008
0.006 0.077
0.819 0.813
Conium maculatum
X 3E-04 0.002
0.000 0.000
I.D.
Trifolium hybridum
X 1E-04 0.001
0.000 0.000
I.D.
Tragopogon dubius
X 1E-04 0.001
0.000 0.001
0.749 0.732
Melilotus sum
X 1E-04 0.001
0.000 0.002
0.750 0.796
Euphorbia esula
X 1E-04 0.001
0.004 0.057
0.351 0.460
Cynoglossum officinale
X 1E-04 0.001
0.014 0.176
0.239 0.348
Cirsium vulgare
X
0 0.000
0.000 0.002
I.D.
Medicago lupulina
X
0 0.000
0.000 0.002
I.D.
Rumex crispus
X
0 0.000
0.000 0.004
I.D.
Lactuca serriola
X
0 0.000
0.001 0.008
I.D.
Trifolium repens
X
0 0.000
0.001 0.010
I.D.
Silene noctiflora
X
0 0.000
0.001 0.012
I.D.
Kochia scoparia
X
0 0.000
0.001 0.014
I.D.
Stellaria media
X
0 0.000
0.003 0.038
I.D.
Chenopodium album
X
0 0.000
0.005 0.069
I.D.
Centaurea maculosa
X 0.000 0.000
0.006 0.077
0.368 0.441
Galeopsis tetrahit
X
0 0.000
0.007 0.088
I.D.
Atriplex heterosperma
X
0 0.000
0.039 0.512
I.D.
Smilacina stellata
Glycyrrhiza lepidota
Solidago gigantea
Apocynum sibiricum
Rudbeckia laciniata
Equisetum pratense
Urtica dioica
Equisetum laevigatum
Polygonum sp.
Achillea millefolium
Equisetum sp.
Vicia americana
Mentha arvensis
Geum macrophyllum
Galium aparine
Plantago major
Solidago missouriensis
Equisetum arvense
Equisetum variegatum
Fragaria vesca
Asclepias speciosa
Antennaria microphylla
Aster ascendens
Avrg cvr of native forb spp, ungr
Avrg cvr of native forb spp, grzd
Avrg cvr of forb species, ungr
Avrg cvr of forb species, grzd
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
0.068
0.061
0.131
0.161
0.023
0.022
0.012
0.005
0.005
9E-04
4E-04
3E-04
1E-04
1E-04
1E-04
1E-04
1E-04
1E-04
1E-04
1E-04
0
0
0
0
0
0
0
0.183
0.173
0.092
0.041
0.036
0.007
0.003
0.002
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.003
0.048
0.000
0.000
0.000
0.000
0.000
0.000
0.001
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.001
0.001
0.007
0.033
0.627
0.002
0.000
0.002
0.000
0.000
0.002
0.008
0.000
0.000
0.000
0.000
0.000
0.000
0.002
0.001
0.001
0.002
0.004
0.010
0.010
0.085
0.279
0.374
0.084
I.D.
0.367
I.D.
I.D.
0.674
0.449
I.D.
I.D.
I.D.
I.D.
I.D.
I.D.
0.862
I.D.
I.D.
I.D.
I.D.
I.D.
I.D.
I.D.
0.529
0.007
0.420
0.017
0.227
0.687
0.546
0.863
0.578
226
Table 24. Comparison of ungrazed and grazed Populus angustifolia sites, cont'd.
T test ungr v grzd
UNGRAZED
GRAZED
GRAMINOIDS
Avrg Total
Avrg Total
Separate Pooled
Cover Cover Cover Cover
variance variance
Cvr non-ntv grass/cvr grass, ungr
79%
Cvr non-ntv grass/cvr grass, grzd
75%
Avrg cvr of non-ntv grass spp, ung 0.164
Avrg cvr of non-ntv grass spp, gr
0.313
0.071 0.115
Elymus repens
X 0.013 0.100
0.139 1.808
0.044 0.094
Phalaris arundinacea
X 0.053 0.423
0.000 0.000
0.109 0.028
Poa pratensis
X 0.049 0.395
0.085 1.100
0.398 0.485
Bromus inermis
X 0.046 0.364
0.059 0.762
0.742 0.772
Dactylis glomerata
X 0.004 0.031
0.027 0.346
0.285 0.393
Agropyron cristatum
X 3E-04 0.002
0.000 0.000
I.D.
Elymus hispidus
X
0 0.000
0.000 0.001
I.D.
Poa compressa
X
0 0.000
0.000 0.002
I.D.
Bromus tectorum
X
0 0.000
0.000 0.004
I.D.
Phleum pratense
X
0 0.000
0.004 0.047
I.D.
Agrostis stolonifera
Elymus smithii
Elymus trachycaulus/E. sp.
Juncus balticus
Carex microptera
Carex sp.
Elymus cinereus
Poa palustris
Carex aquatilis
Avrg cvr of native grass spp, ungr
Avrg cvr of native grass spp, grzd
Avrg cvr of grass species, ungr
Avrg cvr of grass species, grzd
N
N
N
N
N
N
N
N
N
0.037
0.072
0.202
0.385
0.028
0.007
0.002
5E-04
3E-04
1E-04
0
0
0
0.224
0.056
0.012
0.004
0.002
0.001
0.000
0.000
0.000
0.054
0.001
0.000
0.000
0.000
0.001
0.002
0.002
0.012
0.708
0.012
0.000
0.000
0.000
0.007
0.024
0.030
0.159
0.454
0.381
I.D.
I.D.
I.D.
0.468
I.D.
I.D.
I.D.
0.515
0.249
0.412
0.456
0.010
0.029
0.562
227
Table 25. Comparison of ungrazed vs. grazed Populus deltoides sites, cover data and
t test results. Species grouped by life form, then in order by cover.
UNGRAZED SITES (n = 17) (0.0% cow pie)
AvCvr StDev T tests,
Sep Var. Pool Var.
Cover of non-ntv spp/cover of all spp, ungr
0.423 0.207 grazed vs.
0.576 0.575
Average cover of species/ungrazed site
1.563 0.301 ungrazed.
0.996 0.996
Percent cover of non-native species/ungr
28%
14%
0.772 0.773
AvCvr StDev
GRAZED SITES (n = 17) (0.8% cow pie)
Cover of non-native species/cover of all species, grzd
0.450 0.234
Average cover of all species/grazed site
1.535 0.252
Percent cover of non-native species/grazed site
28%
12%
UNGRAZED
GRAZED
T test ungr v. grzd
Native/Non-native
Avrg Sum
Avrg Sum
Separate Pooled
TREES
N/X Cover Cover Cover Cover
variance variance
Avrg cvr of non-native tree spp, ungr
0
Avrg cvr of non-native tree spp, grzd
0
Salicaceae Populus deltoides
N 0.745 13.630 0.792 13.480
0.585 0.583
Oleaceae Fraxinus pennsylvanica
N 0.012 0.198 0.001 0.011
0.234 0.226
Salicaceae Populus angustifolia
N 0.000 0.000 0.014 0.240 Insufficient Data
Avrg cvr of tree spp, ungr
0.813
Avrg cvr of tree spp, grzd
0.808
0.868 0.870
SHRUBS
Cvr non-ntv shrubs/cvr all shrubs, ungr 42%
Cvr non-ntv shrubs/cvr all shrubs, gr
25%
Avrg cvr of non-native shrub spp, ungr 0.152
Avrg cvr of non-ntv shrub spp, grzd
0.092
0.413 0.412
Elaeagnaceae Elaeagnus angustifolia
X 0.149 2.541 0.092 1.563
0.365 0.365
Asteraceae Artemisia absinthium
X 0.002 0.038 2E-04 0.004
0.192 0.184
Anacardiaceae Toxicodendron rydbergii
N 0.078 1.332 0.011 0.192
0.108 0.101
Caprifoliaceae Symphoricarpos occidentalis
N 0.047 0.803 0.071 1.210
0.584 0.583
Cupressaceae Juniperus scopulorum
N 0.039 0.666 8E-04 0.014
0.184 0.175
Rosaceae Rosa sayi/R. woodsii
N 0.016 0.263 0.018 0.300
0.904 0.905
Vitaceae Vitis riparia
N 0.012 0.211 0.003 0.053
0.367 0.362
Cornaceae Cornus stolonifera
N 0.011 0.184 0.000
0 I. D.
Anacardiaceae Rhus trilobata
N 0.011 0.181 0.017 0.295
0.612 0.611
Elaeagnaceae Shepherdia argentea
N 0.008 0.143 0.021 0.364
0.565 0.561
Ranunculaceae Clematis ligusticifolia
N 0.008 0.138 0.016 0.266
0.518 0.515
Salicaceae Salix amygdaloides
N 0.008 0.131 0.000
0 I. D.
Vitaceae Parthenocissus inserta
N 0.007 0.123 0.001 0.016
0.301 0.293
Grossulariaceae Ribes aureum
N 0.007 0.117 0.001 0.013
0.322 0.314
Salicaceae Salix exigua
N 0.004 0.064 0.000
0 I. D.
Asteraceae Artemisia dracunculus
N 0.002 0.041 0.000
0 I. D.
Grossulariaceae Ribes setosum
N 0.001 0.020 0.000 0.002
0.237 0.228
Rosaceae Prunus virginiana
N 6E-04 0.010 0.000 0.001
0.28 0.272
Asteraceae Artemisia frigida
N 6E-05 0.001 0.001 0.014
0.294 0.287
Asteraceae Artemisia cana
N 0.023 0.000 0.000 0.399 I. D.
Salicaceae Salix rigida
N 1E-04 0.000 0.000 0.002 I. D.
Avrg cvr of native shrub spp, ungr
0.261
Avrg cvr of native shrub spp, grzd
0.185
0.416 0.415
Avrg cvr of shrub spp, ungr
0.412
Avrg cvr of shrub spp, grzd
0.277
0.310 0.315
228
Table 25. Comparison of ungrazed vs. grazed Populus deltoides sites, cont'd.
UNGRAZED
GRAZED
FORBS
Avrg Sum
Avrg Sum
Cover Cover Cover Cover
Cvr non-ntv forbs/cvr all forbs, ungr
32%
Cvr non-ntv forbs/cvr all forbs, grzd
70%
Avrg cvr of non-native forb spp, ungr
0.022
Avrg cvr of non-native forb spp, grzd
0.083
Euphorbiaceae Euphorbia esula
X 0.004 0.060 0.018 0.308
Asteraceae Arctium minus
X 0.006 0.110 0.000 0.001
Solanaceae Solanum dulcamara
X 0.006 0.095 0.001 0.011
Asteraceae Cirsium arvense
X 0.003 0.048 0.012 0.197
Asteraceae Taraxacum officinale
X 7E-04 0.012 0.019 0.316
Fabaceae Melilotus alba/officinalis
X 0.001 0.017 0.002 0.033
Fabaceae Medicago lupulina
X 4E-04 0.006 0.005 0.082
Lamiaceae Nepeta cataria
X 3E-04 0.005 0.000 0.002
Scrophulariaceae Verbascum thapsus
X 3E-04 0.005 0.001
0.01
Chenopodiaceae Chenopodium album
X 2E-04 0.003 0.009 0.149
Asteraceae Sonchus uliginosus/asper
X 2E-04 0.003 0.000
0
Asteraceae Tanacetum vulgare
X 2E-04 0.003 0.000 0.001
Asteraceae Cirsium vulgare
X 1E-04 0.002 0.000
0
Brassicaceae Sisymbrium loeselii
X 1E-04 0.002 0.004
0.06
Polygonaceae Polygonum convulvulus
X 6E-05 0.001 0.000
0
Boraginaceae Cynoglossum officinale
X 6E-05 0.001 0.000 0.005
Apiaceae Conium maculatum
X
0 0.000 0.000 0.001
Brassicaceae Camelina microcarpa
X
0 0.000 0.000 0.001
Brassicaceae Capsella bursa - pastoris
X
0 0.000 0.000 0.001
Brassicaceae Descurainia sophia
X
0 0.000 0.000 0.001
Chenopodiaceae Kochia scoparia
X
0 0.000 0.000 0.002
Chenopodiaceae Salsola kali
X
0 0.000 0.000 0.002
Asteraceae Centaurea maculosa
X
0 0.000 0.000 0.003
Liliaceae Asparagus officinalis
X
0 0.000 0.000 0.003
Fabaceae Trifolium fragiferum
X
0 0.000 0.000 0.007
Asteraceae Tragopogon dubius
X
0 0.000 0.001 0.009
Asteraceae Lactuca serriola
X
0 0.000 0.001 0.012
Chenopodiaceae Atriplex heterosperma
X
0 0.000 0.001 0.014
Fumariaceae Fumaria officinalis
X
0 0.000 0.011 0.186
Urticaceae Parietaria pensylvanica
N 0.005 0.084 0.003 0.056
Asteraceae Solidago mollis
N 0.005 0.080 0.000
0
Apocynaceae Apocynum sibiricum
N 0.005 0.077 0.000 0.002
Liliaceae Smilacina stellata
N 0.003 0.043 0.000 0.005
Fabaceae Glycyrrhiza lepidota
N 0.002 0.033 0.012
0.2
Asteraceae Solidago gigantea
N 0.001 0.022 0.000 0.001
Asclepiadaceae Asclepias speciosa
N 0.001 0.019 0.000 0.002
Ranunculaceae Anemone sp.
N 6E-04 0.010 0.000
0
Solanaceae Solanum sarrachoides
N 5E-04 0.008 0.000
0
Rubiaceae Galium aparine
N 4E-04 0.007 0.000
0
Asteraceae Aster ascendens
N 4E-04 0.007 0.000 0.001
Asclepiadaceae Asclepias verticillata
N 2E-04 0.004 0.000
0
Asteraceae Solidago occidentalis
N 2E-04 0.004 0.000 0.001
T test ungr v. grzd
Separate
Pooled
variance
variance
0.036
0.343
0.318
0.377
0.294
0.105
0.39
0.089
0.583
0.578
0.241
I. D.
0.413
I. D.
0.348
I. D.
0.142
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
0.776
I. D.
0.150
0.152
0.181
0.191
0.22
I. D.
I. D.
I. D.
0.339
0.223
0.316
0.032
0.337
0.311
0.371
0.288
0.095
0.387
0.080
0.581
0.576
0.233
0.41
0.341
0.137
0.776
0.141
0.143
0.172
0.181
0.212
0.333
0.229
0.311
229
Table 25. Comparison of ungrazed vs. grazed Populus deltoides sites, cont'd.
UNGRAZED
GRAZED
FORBS, cont'd.
Avrg Sum
Avrg Sum
Cover Cover Cover Cover
Equisetaceae Equisetum hyemale
N 1E-04 0.002 0.000
0
Violaceae Viola sp.
N 7E-04 0.002 0.000 0.011
Asteraceae Ambrosia psilostachya
N 1E-04 0.002 0.011 0.181
Caprifoliaceae Lonicera sp.
N 6E-05 0.001 0.000
0
Equisetaceae Equisetum variegatum
N 6E-05 0.001 0.000
0
Lamiaceae Mentha arvensis
N 6E-05 0.001 0.000
0
Polygonaceae Polygonum sp.
N 6E-05 0.001 0.000
0
Primulaceae Lysimachia ciliata
N 6E-05 0.001 0.000
0
Plantiginaceae Plantago major
N 6E-05 0.001 0.000 0.001
Asteraceae Conyza canadensis
N
0 0.000 0.000 0.001
Asteraceae Helianthus annuus
N
0 0.000 0.000 0.001
Asteraceae Solidago spathulata
N
0 0.000 0.000 0.001
Brassicaceae Rorippa palustris
N
0 0.000 0.000 0.001
Fabaceae Vicia americana
N
0 0.000 0.000 0.001
Ranunculaceae Thalictrum dasycarpum
N
0 0.000 0.000 0.001
Verbenaceae Verbena hastata
N
0 0.000 0.000 0.001
Brassicaceae Lepidium densiflorum
N
0 0.000 0.000 0.003
Fabaceae Psoralea lanceolata
N
0 0.000 0.000 0.005
Asteraceae Xanthium strumarium
N
0 0.000 0.000 0.006
Asteraceae Grindelia squarrosa
N
0 0.000 0.000 0.006
Polygonaceae Polygonum achoreum
N
0 0.000 0.001 0.010
Asteraceae Ambrosia trifida
N
0 0.000 0.001 0.024
Avrg cvr native forb spp, ungr
0.024
Avrg cvr native forb spp, grzd
0.031
Avrg cvr of forb spp, ungr
0.046
Avrg cvr of forb spp, grzd
0.114
GRAMINOIDS
Cvr non-ntv grmnd/cvr all grmnd, ung
Cvr non-ntv grmnd/cvr all grmnds, grz
Avrg cvr of non-ntv grmnd spp, ungr
Avrg cvr of non-ntv grmnd spp, grzd
Poaceae Bromus inermis
Poaceae Poa pratensis
Poaceae Elymus repens
Poaceae Phalaris arundinacea
Poaceae Poa compressa
Poaceae Alopecurus arundinaceus
Poaceae Festuca arundinacea
Poaceae Setaria viridis
Poaceae Bromus mollis
Poaceae Bromus japonicus
Poaceae Bromus tectorum
Poaceae Elymus trachycaulus/A. sp.
Poaceae Elymus canadensis
Poaceae Calamovilfa longifolia
89%
81%
0.250
0.274
X
X
X
X
X
X
X
X
X
X
X
T test ungr v. grzd
Separate
Pooled
variance
variance
I. D.
0.341
0.089
I. D.
I. D.
I. D.
I. D.
I. D.
1.000
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I.D.
I. D.
I. D.
I. D.
0.335
0.079
1.000
0.072
0.068
0.147
0.043
0.04
0.017
0.002
1E-04
1E-04
0
0
0
0
2.504
0.736
0.672
0.290
0.040
0.002
0.002
0.000
0.000
0.000
0.000
0.125
0.087
0.043
0.007
0.002
0.000
0.000
0.000
0.001
0.002
0.009
2.120
1.472
0.728
0.121
0.028
0
0
0.001
0.014
0.031
0.149
0.528
0.732
0.137
0.903
0.408
0.792
I. D.
I. D.
I. D.
I. D.
I. D.
0.160
0.529
0.732
0.136
0.903
0.408
0.791
N 0.018
N 0.013
N 0.006
0.300
0.223
0.098
0.008
0.000
0.004
0.131
0.004
0.071
0.541
0.269
0.811
0.539
0.261
0.811
0.150
230
Table 25. Comparison of ungrazed vs. grazed Populus deltoides sites, cont'd.
UNGRAZED
GRAZED
GRAMINOIDS, cont'd.
Avrg Sum
Avrg Sum
Cover Cover Cover Cover
Poaceae Agrostis stolonifera
N 0.005 0.082 0.003 0.058
Poaceae Muhlenbergia racemosa
N 2E-04 0.004 0.001 0.011
Cyperaceae Carex sp.
N 2E-04 0.003 0.000 0.001
Poaceae Spartina pectinata
N 6E-05 0.001
0
Poaceae Stipa viridula
N
0 0.000 0.000 0.001
Poaceae Sporobolus cryptandrus
N
0 0.000 0.001 0.012
Poaceae Spartina gracilis
N
0 0.000 0.001 0.014
Poaceae Stipa comata
N
0 0.000 0.002
0.03
Poaceae Hordeum jubatum
N
0 0.000 0.003 0.045
Poaceae Boutelua gracilis
N
0 0.000 0.003 0.047
Poaceae Elymus spicatus
N
0 0.000 0.015 0.260
Poaceae Elymus smithii
N
0 0.000 0.022 0.369
Avrg cvr of native grass spp, ungr
0.042
Avrg cvr of grass spp, ungr
0.292
Avrg cvr of native grass spp, grzd
0.062
Avrg cvr of grass spp, grzd
0.336
T test ungr v. grzd
Separate
Pooled
variance
variance
0.775
0.34
0.413
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
I. D.
0.083
0.775
0.339
0.41
0.367
0.368
0.074
Table 26. Comparison of cover, richness and percent non-native species across grazed riparian plant communities.
Vegetation Type
Tree
X*
#
Ntv
Total
#
Forb
% Non # Non
Ntv
Ntv
#
Ntv
Total
#
Graminoid
% Non # Non
#
Ntv
Ntv
Ntv
Total
#
2
0.7
0.033
40%
11%
0%
2
0.3
0.000
3
5
1.7
2
0.025 0.025
47%
47%
50%
22
7.5
0.022
25
7.7
0.020
47
15.2
0.042
25%
31%
54%
5
1.5
0.025
15
4.3
0.009
20
5.8
0.035
2
1.0
0.012
33%
13%
0%
1
0.25
0
2
3
1.0 1.25
0.003 0.003
34%
43%
41%
11
4.3
0.025
21
7.3
0.090
32
11.5
0.113
24%
31%
11%
5
1.3
0.012
16
5.0
0.047
21
6.3
0.059
4
0.6
0.024
23%
9%
1%
3
0.5
0.006
10
13
3.1
3.6
0.423 0.429
42%
52%
56%
21
6.5
0.091
29
5.8
0.114
50
12.3
0.205
28%
46%
41%
8
2.7
0.108
21
3.9
0.118
29
6.6
0.226
2
1.1
0.858
0%
0%
0%
0
0
0.000
16
16
3.5
3.5
0.078 0.078
59%
69%
55%
24
4.8
0.101
17
2.3
0.061
41
7.1
0.161
53%
77%
75%
9
3.3
0.315
8
1.0
0.070
17
4.3
0.385
3
1.2
0.808
20%
24%
25%
3
0.8
0.092
15
15
3.4
4.2
0.185 0.277
49%
59%
71%
30
4.7
0.083
31
3.2
0.031
61
7.9
0.114
39%
63%
81%
9
2.5
0.274
14
2.0
0.062
23
4.5
0.336
* No non-native tree species were found. Elaeagnus angustifolia was classified as a shrub, per the USDA on-line plants database.
231
Gravelbar (n = 6)
Richness/all sites
0
Richness/each site
0
Cover
0
Sandbar (n = 4)
Richness/all sites
0
Richness/each site
0
Cover
0
Salix exigua (n = 10)
Richness/all sites
0
Richness/each site
0
Cover
0
Populus angustifolia (n = 13)
Richness/all sites
0
Richness/each site
0
Cover
0
Populus deltoides (n = 17)
Richness/all sites
0
Richness/each site
0
Cover
0
Total
Shrub
% Non # Non
Ntv
Ntv
Table 26. Comparison of cover, richness and percent non-native species across grazed riparian plant communities, cont'd.
Vegetation Type
# Non
Ntv
#
St Dev
Ntv
Total
#
St Dev
39%
39%
37%
N/A
10%
27%
29
9.3
0.048
N/A
4.5
0.040
45
14.4
0.087
74
23.7
0.134
N/A
11.5
0.026
29%
34%
26%
N/A
16%
24%
17
5.8
0.037
N/A
2.1
0.022
41
14.3
0.152
58
20
0.186
N/A
14
0.141
33%
41%
25%
N/A
9%
20%
32
9.7
0.203
N/A
3.9
0.173
64
13.4
0.679
96
23.1
0.885
N/A
6.4
0.340
43%
50%
27%
N/A
10%
14%
33
8.1
0.416
N/A
3
0.249
43
7.9
1.067
76
16
1.483
N/A
4.9
0.226
40%
50%
28%
N/A
10%
12%
42
8.1
0.450
N/A
3.8
0.234
63
9.8
1.086
105
17.9
1.535
N/A
6.9
0.252
232
Gravelbar (n = 6)
Richness/all sites
Richness/each site
Cover
Sandbar (n = 4)
Richness/all sites
Richness/each site
Cover
Salix exigua (n = 10)
Richness/all sites
Richness/each site
Cover
Populus angustifolia (n = 13)
Richness/all sites
Richness/each site
Cover
Populus deltoides (n = 17)
Richness/all sites
Richness/each site
Cover
SUMMARY
% Non
Ntv
St Dev
Table 27. Environmental variable averages at ungrazed vs. grazed sites, by riparian plant community.
Gravelbars
Environmental variables Ungrazed
Grazed
avrg st dev avrg st dev
Mile on river*
110.4 106.6 130.0 178.6
Gage height (ft)
7.1
2.0
6.6
2.9
Height above water (ft)
4.7
2.1
2.8
2.7
Height above water (m)
1.4
0.6
0.9
0.8
*Measured from Big Creek, MT, going downriver
233
Populus angustifolia
Populus deltoides
Salix exigua
Sandbars
Environmental variables Ungrazed
Grazed
Ungrazed
Grazed
Ungrazed
Grazed
Ungrazed
Grazed
avrg st dev avrg st dev avrg st dev avrg st dev avrg st dev avrg st dev avrg st dev avrg st dev
Mile on river*
48.4 37.87
31 26.98 304.9 129.7 315.4 131.5 161.5 146.5 97.2 107.4 205.3 162.4 263.2 264.2
Gage height (ft)
11.2
2.3 11.5
1.9
16.7
5.5 14.7
3.8
9.7
2.0
9.5
2.3
6.9
2.3
7.9
2.9
Height above water (ft)
7.7
2.7
8.6
2.5
14.3
5.6 12.3
3.5
6.8
2.4
6.8
2.4
4.6
2.4
5.1
3.0
Height above water (m)
2.4
0.8
2.6
0.8
4.4
1.7 3.7
1.1
2.1
0.7
2.1
0.7
1.4
0.7
1.5
0.9
Depth to gravel (cm)
111
48
74
38
153
38 176
93
111
40 125
54
28
24
32
34
CaCO3% Equiv
0.4
0.5
0.2
0.2
3.4
1.6
3.3
1.3
1.8
1.8
1.0
1.4
1.5
1.7
2.3
2.6
pH (1 to 1)
7.8
0.2
7.9
0.3
8.1
0.3
8.2
0.2
8.1
0.4
8.1
0.3
8.1
0.5
8.0
0.3
Total C%
2.85 1.152 3.78 4.409
2.26 1.04
2.3
1.3
1.20 1.09 0.77 0.46
0.56 0.23 0.89 0.47
% Organic C
2.80 1.149 3.75 4.404
1.86 0.96
1.9
1.3
0.99 1.13 0.65 0.40
0.37 0.06 0.62 0.21
Total N%
0.168 0.065 0.271 0.358 0.123 0.069 0.133 0.095 0.065 0.078 0.041 0.025 0.023 0.005 0.032 0.012
Sand %
36
14
56
10
42
20 45.5 18.4
53
17
67
13
72
11
59
15
Silt %
49
12
32
8
38
12 35.4 10.6
35
13
23
10
21
8
30
11
Clay %
15
4
12
3
20
10 19.1
9.5
12
5
10
6
7
3
11
5
EC mmhos/cm, 1 to 1
0.45 0.221 0.65 0.677
0.47 0.24 0.46 0.52
0.51 0.36 0.37 0.24
0.37 0.09 0.35 0.13
Table 28. Shrub cover of ungrazed vs. grazed Populus deltoides sites; releve and cover data.
Sites are segregated by ungrazed/grazed, then in order by DBH. Species are in order by life form, then by average cover.
USP U2P2 UYP UWP UZP2 UZP UXP UVP UWP2 URP2 U1P UPP U4P U1P2 URP
UNGRAZED STUDY SITES
Percent cover cow pie
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
DBH, three largest trees
33
36
38
40
41
44
50
54
56
65
71
72
73
75
76
Mile on river from Big Creek, MT
203.0 491.5 361.2 258.5 372.2 372.2 308.3 251.5 258.5 193.7 479.3 144.0 509.8 479.3 193.7
Populus deltoides
N
SHRUBS (UNGRAZED)
0.802 0.800 0.920 0.920 0.510 1.000 1.000 0.960 0.960
UOP
USP2
0
0
82
112
103.0 203.0
0.720
0.840 0.520 0.960 0.960 0.440 0.120 1.000 1.000
AvCvr
Avrg cover of non-native shrub spp
0.152 0.003 0.000 0.142 0.160 0.048 0.359 0.152 0.000
0.119
0.442 0.106 0.210 0.188 0.000 0.630 0.000 0.020
Elaeagnus angustifolia
Artemisia absinthium
X
0.149 0.001
0.119
0.426 0.106 0.210 0.188
X
0.002 0.002
Toxicodendron rydbergii
Symphoricarpos occidentalis
Juniperus scopulorum
Rosa sayi
Vitis riparia
Cornus stolonifera
Rhus trilobata
Shepherdia argentea
Clematis ligusticifolia
Salix amygdaloides
Parthenocissus inserta
Ribes aureum
Salix exigua
Artemisia dracunculus
Ribes setosum
Rosa sp.
Prunus virginiana
Solanum sarrachoides
Artemisia frigida
Artemisia cana
Salix rigida
Avrg cvr of ntv shrub spp
Average cover of shrub spp
N
0.078
N
0.047
N
0.039
N
0.014
N
0.012 0.001 0.004
N
0.011 0.004
N
0.011
N
0.008 0.001
N
0.008 0.011 0.012
N
0.008 0.020
N
0.007
N
0.007 0.002
N
0.004 0.064
N
0.002
N
0.001 0.001
N
0.001
N
0.001
N
0.000
N
0.000
N
0.000
0.630
0.016
0.010
0.158
0.020
0.004
0.270
0.001 0.014 0.021
0.055 0.230
0.290
0.030
0.570
0.088 0.170 0.004
0.220
0.256
0.005
0.410
0.044 0.094
0.016
0.084
0.164
0.028
0.004
0.001 0.009
0.001
0.078
0.062
0.083
0.020
0.061
0.060
0.080 0.002
0.018
0.100
0.051
0.001
0.082
0.002
0.100
0.014
0.001
0.027
0.009
0.102
0.000 0.006
0.007
0.041
0.005
0.014
0.016
0.008 0.001
0.001
0.008
0.001
0
0.261 0.104 0.126 0.000 0.087 0.000 0.001 0.243 0.035
0.000
0.588 0.863 0.144 0.530 0.343 0.421 0.043 0.904
0.412 0.107 0.126 0.142 0.247 0.048 0.360 0.395 0.035
0.119
1.030 0.969 0.354 0.718 0.343 1.051 0.043 0.924
234
N
0.142 0.160 0.048 0.359 0.152
Table 28. Shrub cover of ungrazed vs. grazed Populus deltoides sites; releve and cover data, cont'd.
Sites are segregated by ungrazed/grazed, then in order by DBH. Species are in order by life form, then by average cover.
G2P2 G2P G3P G1P G1P2 GPP2 GUP GXP GXP2 GRP2 GPP GRP GSP GZP GZP2
GRAZED STUDY SITES
Percent cover cow pie
0.000 0.000 0.000 0.004 0.014 0.028 0.016 0.018 0.018 0.000 0.006 0.000 0.000 0.005 0.011
DBH, three largest trees
28
41
44 ?
?
54
55
66
66
70 c. 72
80
84
88
88
Mile on river from Big Creek, MT
491.5 491.5 491.5 479.3 479.3 144.1 248.4 308.3 308.3 193.7 143.9 193.7 203.0 372.2 372.2
Populus deltoides
N
SHRUBS (GRAZED)
0.793 0.880 1.000 0.880 0.920 0.960
0.880 0.960 0.640
0.600
0.760 0.920 0.680 0.600 0.600
0.092 0.003 0.001 0.117 0.000 0.078
0.000 0.582 0.000
0.048
0.038 0.001 0.578 0.000 0.000
0.000 0.582
0.048
0.038 0.001 0.574
AvCvr
Average cover of non-native shrub spp
GTP
0.008
GTP2
0.016
96
103
220.4
220.4
0.520 0.760
0.920
0.000 0.000
0.121
Shrubs PODE Cover
Elaeagnus angustifolia
Artemisia absinthium
X
0.092 0.003 0.001 0.117 0.000 0.078
X
0.000
Toxicodendron rydbergii
Symphoricarpos occidentalis
Juniperus scopulorum
Rosa sayi
Vitis riparia
Cornus stolonifera
Rhus trilobata
Shepherdia argentea
Clematis ligusticifolia
Salix amygdaloides
Parthenocissus inserta
Ribes aureum
Salix exigua
Artemisia dracunculus
Ribes setosum
Rosa sp.
Prunus virginiana
Solanum sarrachoides
Artemisia frigida
Artemisia cana
Salix rigida
Avrg cvr of ntv shrub spp, grzd
Average cover of shrub spp
N
0.011 0.002 0.002
N
0.071 0.003 0.011
N
0.001
N
0.014 0.004 0.004
N
0.003 0.001 0.001 0.001
N
0.000
N
0.017
N
0.021
N
0.016 0.108 0.008
N
0.000
N
0.001 0.005 0.001 0.004 0.004 0.002
N
0.001 0.004
N
0.000
N
0.000
N
0.000
N
0.004
N
0.000
N
0.000
N
0.001 0.001
N
0.023
N
0.000
0.000
0.020
0.018
0.001
0.121
0.004
0.260 0.001
0.000
0.162
0.006
0.380
0.526
0.010
0.118
0.111
0.050
0.000
0.014
0.010
0.190 0.024
235
0.041
0.030
0.364
0.150
0.002
0.001
0.006
0.021
0.042
0.002
0.001
0.012
0.001
0.001
0.070
0.328
0.002
0.185 0.128 0.030 0.005 0.024 0.022
0.042 0.000 0.026
0.377
0.472 0.025 0.150 0.670 0.070
0.329 0.650
0.121
0.277 0.131 0.031 0.122 0.024 0.100
0.042 0.582 0.026
0.425
0.510 0.026 0.728 0.670 0.070
0.329 0.650
0.242
236
Table 29. Species richness found by sampling lower Yellowstone River sites
by two methods.
Community
1980 (Boggs 1984)
2001 (our data)
Species/ # of nonPercent
Species/ # of nonPercent
site
natives/site non-native site
natives/site non-native
Sandbar
9.8
2.2
22.40%
25.2
11.3
44.8%
Salix exigua
15.9
4.1
25.8%
22.0
9.6
43.6%
P. deltoides
16.8
2.0
11.9%
19.0
8.3
43.7%
Average
20.0%
44.0%
237
APPENDIX B
FIGURES
238
From Zelt, 1999
Figure 1 - The Yellowstone River Basin. The River flows out of Yellowstone
Lake in Wyoming, north into Montana and turns east at Livingston. It passes
through Billings, Miles City and Glendive before crossing in to North Dakota
and emptying into the Missouri.
239
From Zelt, 1999
Figure 2. Potential natural vegetation of the Yellowstone River Basin.
240
From Zelt, 1999
Figure 3. Physiographic provinces of the Yellowstone River Basin.
241
From Zelt, 1999
Figure 4. Average annual precipitation, Yellowstone River Basin.
242
Modified from Zelt 1999
Figure 5. Mean daily precipitation and temperature at selected stations along the
Yellowstone River.
243
From Zelt, 1999
Figure 6. Generalized geology of the Yellowstone River Basin.
244
Figure 7. Sites along the upper Yellowstone River, from Big Creek and Emigrant through Springdale to Billings.
Capital letters on the map are the middle digit of the site code, e.g. UJN and GJX are at or by Sheep Mountain FAS.
245
Figure 7. Sites along the lower Yellowstone River, from Worden (Gritty Stone Fishing Access Site) to Sidney.
Letters & numbers on the map are the middle digit of the site code, e.g. GXX and UXP are at Far West FAS.
246
Figure 8. Gravelbar at Emigrant West Fishing Access Site.
Seedlings of Populus angustifolia are the dominant cover.
Figure 9. Gravelbar at Emigrant West Fishing Access Site. P angustifolia seedlings
dominate the cobble deposited on the level top of the gravelbar (right), while Salix exigua
seedlings are establishing on the small sandy bank (left).
Figure 10. Gravel size distribution on gravelbars
300
200
Largest gravel size (size 100)
Gravel size 90
Gravel size 75
150
Median gravel size
Gravel size 25
Gravel size 10
100
50
0
0
50
100
150
200
River mile from Big Creek, MT
250
300
350
247
W idth of gravel (cobble) in m m
250
248
Figure 11. Sandbar at Seven Sisters Wildlife Management Area.
Note Salix exigua seedlings establishing.
Figure 12. Salix exigua thicket with taller Salix amygdaloides behind it.
Far West Fishing Access Site.
249
Figure 13. Populus angustifolia forest at Grey Owl Fishing Access Site.
250
Figure 14. Populus deltoides forest at Far West Fishing Access Site.
251
Figure 15. Grass growing in a sandy patch of a gravelbar, at Emigrant West
fishing access site.
252
Figure 16. Succession on a gravel bar near Emigrant, Montana (site UCA). The
upriver end of the island is in the foreground of the photo, where Populus
angustifolia seedlings are establishing. Behind them, and higher in elevation, are
young P angustifolia mixed with S exigua. Pole sized and then mature P
angustifolia can be seen in the background. There were no signs of grazing on
this island.
Figure 17. Growth of Populus angustifolia community from gravelbars
1
0.9
0.8
0.7
Trees
Other shrubs
Salix exigua
Forbs
Graminoids
0.5
0.4
0.3
0.2
0.1
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
-0.1
Germination (1), through gravelbar (2) and willow (3) to mature trees (4)
1.6
1.8
253
Percent cover
0.6
Figure 18. Growth of Populus deltoides community from sandbars
0.9
0.8
0.7
0.5
Trees
Other shrubs
Salix exigua
Forbs
Graminoids
0.4
0.3
0.2
0.1
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
-0.1
From germination (1), through sandbar (2) and willow (3) to mature trees (4)
4.0
4.5
254
Percent cover
0.6
Figure 19. Height above water of research sites
8.0
7.0
5.0
Populus angustifolia sites
Populus deltoides sites
4.0
Salix exigua (willow) sites
Sandbar sites
Gravelbar sites
3.0
2.0
1.0
0.0
0
100
200
300
River mile from Big Creek, MT
400
500
600
255
H e ig h t a b o v e w a te r in m e te rs
6.0
Figure 20. Depth to gravel at research sites
500
450
400
300
Cottonwood sites
250
Willow sites
Sandbar sites
200
150
100
50
0
0
100
200
300
River mile from Big Creek, MT
400
500
600
256
D e p th to g ra v e l (c m .)
350
Figure 21. Soil CaCO3 percent equivalency at research sites
6
4
cottonwood sites
3
willow sites
sandbar sites
2
1
0
0
100
200
300
River Mile from Big Creek, MT
400
500
600
257
S oil C aC O 3% eq u iva len cy
5
Figure 22. Soil pH at research sites
10
9
8
7
Cottonwood sites
5
Willow sites
Sandbar sites
4
3
2
1
0
0
100
200
300
River mile from Big Creek, MT
400
500
600
258
p H (1 to 1 )
6
Figure 23. Soil percent organic carbon at ungrazed sites
6.00
4.00
Populus angustifolia sites
Populus deltoides sites
3.00
Willow (Salix exigua) sites
Sandbar sites
2.00
1.00
0.00
0
100
200
300
River Mile from Big Creek, MT
400
500
600
259
P e rc e n t o rg a n ic c a rb o n
5.00
Figure 24. Soil percent nitrogen at ungrazed sites
0.35
0.3
0.2
Populus angustifolia sites
Populus deltoides sites
Salix exigua (willow) sites
Sandbar sites
0.15
0.1
0.05
0
0
100
200
300
River mile from Big Creek, MT
400
500
600
260
S o il p e rc e n t n itro g e n
0.25
Figure 25. Soil texture: percent sand at ungrazed sites
100
90
80
60
Populus angustifolia sites
Populus deltoides sites
50
Salix exigua (willow) sites
Sandbar sites
40
30
20
10
0
0
100
200
300
River mile from Big Creek, MT
400
500
600
261
P e rc e n t s a n d
70
Figure 26. Soil Texture: percent silt at ungrazed sites
70
60
40
Populus angustifolia sites
Populus deltoides sites
Salix exigua (willow) sites
Sandbar sites
30
20
10
0
0
100
200
300
River mile from Big Creek, MT
400
500
600
262
P e rc e n t s ilt
50
Figure 27. Soil texture: Percent clay at ungrazed sites
50
45
40
30
Populus angustifolia sites
Populus deltoides sites
25
Salix exigua (willow) sites
Sandbar sites
20
15
10
5
0
0
100
200
300
River mile from Big Creek, MT
400
500
600
263
P e rc e n t c la y
35
Figure 28. Soil electrical conductivity at research sites
3
2
EC mmhos/cm, 1 to 1, cottonwood sites
1.5
EC mmhos/cm, 1 to 1, willow sites
EC mmhos/cm, 1 to 1sandbar sites
1
0.5
0
0
100
200
300
River Mile from Big Creek, MT
400
500
600
264
E C in m m h o s/c m , 1 to 1
2.5
265
Figure 29. Heavily grazed sandbar willows, foothills zone.
The dowel is one meter high.
266
0.015
Figure 30. Ordination of ungrazed vs. grazed gravelbars. The top diagram
shows environmental variables, the lower diagram gives sites codes.
Grv l_sz_100%
Grv l_sz_75%
grazing
ungrazed
grazed
0.005
Grv l_median
-0.005
Grv l_sz_25%
abov e_H2O
gage_ht
riv er_mile
-0.015
Dim2
%sand
Grv l_sz_10%
-0.01
0.00
0.01
0.02
Dim1
0.015
gravel 2D NMS stress = 20.7, mult = .022. Transect G2A deleted,
no (gravel size 90%) among environmental vectors
GIA
grazing
0.005
UIA
ungrazed
grazed
UEA
UDA2
GNA
UXA2
GKA
-0.005
UMA
-0.015
Dim2
UMA2
UXA
UDA
UCA
USA
UJA2
GLA
GLA2
UJA
UWA
URA
-0.01
0.00
0.01
Dim1
0.02
267
Figure 31. Ordination of ungrazed vs. grazed sandbar sites. The top diagram
shows environmental variables, the lower diagram gives site codes.
graz ing
0.02
ungrazed
grazed
soil_depth
silt
N
-0.02
Dim2
sand
abov e_H2O
EC
pH
clay
-0.06
C
CaCO3
riv er_mile
f izz
-0.06
-0.02
0.02
0.06
Dim1
sandbar 2D NMS stress = 13.09, mult=.1
U2B
graz ing
UDB
0.02
UWB
URB
UEB
-0.02
GGB
GKB
UXB
G2B
G2B2
-0.06
Dim2
ungrazed
graz ed
UMB
UXB2
-0.06
-0.02
0.02
Dim1
0.06
268
Figure 32. Ordination of ungrazed vs. grazed Salix exigua communities. The top
diagram shows environmental variables, the lower diagram gives site codes.
0.004
abov e_H2O
gage_ht
riv er_mile
CaCO3
grazing
ungrazed
grazed
clay
0.000
Dim2
f izz
pH
silt
sand
EC
-0.004
C
N
-0.005
0.000
0.005
Dim1
Willow 2D solution stress = 19.45, mult=.015.
0.004
U4Z
GFY
U1Z
grazing
ungrazed
grazed
UJX
0.000
UHX
UXX
GLX
GTX
U2X
USX
UTX UNX2GAX2
GAX
UNX
UCX
UBX
UMX2
UDX
GJX
-0.004
Dim2
GMX
UWX
UKX2
UYX
U1X
URX
UQXUKX
UUX
UOX
GKX
GGX
UMX
GSX
-0.005
0.000
Dim1
0.005
0.003
269
Figure 33. Ordination of ungrazed vs. grazed Populus angustifolia stands. The
top diagram shows environmental variables, the lower diagram gives site codes.
grazing
ungrazed
0.001
pH
C
-0.001
Dim2
grazed
abov e_H2O
gage_ht
clay silt
sand
N
EC
soil_depth
f izz
CaCO3
-0.003
riv er_mile
-0.002
0.000
0.002
0.004
Dim1
0.003
2D solution Populus angustifolia, stress = 19.4, mult. = .004.
grazing
ungrazed
0.001
GGN
UEN
UCN
GHN
GJN
UJN
-0.001
UMN2
GIN2
GFN
GIN
UCN2
GGN2
GBN
GBN3
UNN
UNN2
GKNGNN
UKN
GBN2
-0.003
Dim2
grazed
UEN2 GHN2
-0.002
Dim1
0.000
GMN
UEN3
0.002
0.004
0.004
270
Figure 34. Ordination of ungrazed vs. grazed Populus deltoides stands. The top
diagram shows environmental variables, the lower diagram gives the site codes.
sand
0.000
Dim2
EC
grazing
ungrazed
grazed
N
f izz
pH
C
clay
-0.004
soil_depth
abov e_H2O
gage_ht
riv er_mile
silt
CaCO3
-0.004
0.000
0.004
Dim1
0.004
stress = 20.7 P. deltoides 2D NMS, URP dropped, mult = .01
GRP
URP2
0.000
UWP2
USP2
GTP2
UXP
UPP
G2P2G2P
GPP2
UZP2
U2P
GPP
USP
UZP
GXP2
GRP2
U4P
GTP
UYP
UVP
G1P2UOP
G1PG3P
U2P2
U1P
GXP
-0.004
Dim2
GUP
GSP
GZP
UWP
GZP2
U1P2
-0.004
0.000
Dim1
0.004
271
r_mile
abov e_H2O
soil-d
-0.006
-0.002
sand
grazing
ungrazed
grazed
-0.010
Dim2
0.002
Figure 35. Ordination of Populus angustifolia, P. deltoides and P. acuminata
communities. The cluster in the upper left are grazed and ungrazed
P deltoides stands, the cluster in the upper right are grazed and
ungrazed P angustifolia stands. The six grazed sites in the lower center
are P acuminata stands, the hybrid between the other two Populus
species. The lone grazed site in the lower left is a location with low
cover of P deltoides, and high cover of Elaeagnus angustifolia.
-0.005
0.000
0.005
Dim1
2D NMS cottonwood, sor. dist, stress = 8.3, env mult. = .004